Not every PPC campaign works.
Budgets get wasted.
CPA increases.
ROAS falls.
Lead quality drops.
Tests fail.
And sometimes, despite doing everything you expected to work, performance still moves in the wrong direction.
That isn't automatically a problem in a job interview.
In fact, being able to talk confidently about an underperforming campaign can make you a stronger candidate.
Employers don't expect every PPC professional to have a perfect record.
They want to understand how you respond when things go wrong.
Because managing successful campaigns is useful.
But diagnosing poor performance, making difficult decisions, and learning from mistakes is often where real PPC skill becomes visible.
Don't Try to Pretend Everything Has Always Worked
If an interviewer asks:
"Tell me about a campaign that underperformed."
avoid answering:
"I've never really had one."
Even highly experienced PPC professionals manage campaigns that don't perform as expected.
Markets change.
Competitors react.
Tracking breaks.
Offers fail.
Landing pages underperform.
Automation behaves differently from forecasts.
Pretending every campaign has been successful can make you sound inexperienced or unwilling to discuss mistakes.
A better approach is to choose a genuine example and explain it thoughtfully.
Pick the Right Example
You don't need to choose the biggest disaster of your career.
Pick an example that allows you to demonstrate:
- Analysis
- Problem-solving
- Decision-making
- Communication
- Commercial awareness
- Learning
A useful example might involve:
- A campaign launch that missed its CPA target
- A bidding strategy that reduced performance
- A new market that converted poorly
- A Performance Max test that didn't work
- A landing page that lowered conversion rates
- A lead generation campaign that produced poor-quality leads
- A budget increase that reduced efficiency
The result can be negative.
Your response to it should be strong.
Explain the Original Objective
Start by giving the interviewer context.
What was the campaign supposed to achieve?
For example:
"We launched a new non-brand Search campaign with the aim of generating qualified leads at a CPA below £80."
Or:
"The client wanted to increase ecommerce revenue during a seasonal period while maintaining at least a 4x ROAS."
This establishes the benchmark.
Without knowing the objective, the interviewer can't judge whether the campaign actually underperformed.
Explain What Happened
Be specific.
Instead of saying:
"It didn't perform very well."
say:
"After the first six weeks, CPA was approximately £125 against an £80 target, while lead volume was also below forecast."
Or:
"ROAS fell from around 4.3 to 3.1 after we increased spend."
Numbers make the problem clear.
They also demonstrate that you understand performance in measurable terms.
Don't Immediately Start Making Excuses
One of the easiest ways to weaken your answer is to spend the first two minutes explaining why the failure wasn't your fault.
Maybe:
The client changed the landing page.
Google's algorithm behaved strangely.
The market became more competitive.
The creative team was late.
The tracking wasn't perfect.
Those factors may all be relevant.
But start with ownership.
For example:
"The campaign underperformed against the target, so my first priority was understanding which part of the funnel had changed."
That sounds much stronger than immediately blaming an external factor.
Diagnose Before You Optimise
When performance declines, inexperienced PPC professionals may start changing things immediately.
New bidding strategy.
New keywords.
New campaign structure.
New budgets.
Everything at once.
That can make the problem harder to understand.
A stronger approach is to diagnose first.
Look at where the change occurred.
Was it:
Traffic?
Cost?
Conversion?
Tracking?
Lead quality?
That gives you a logical starting point.
Start with the Performance Funnel
Suppose CPA increases significantly.
You could investigate:
- Impressions
- Clicks
- CTR
- CPC
- Conversion rate
- Conversion volume
If CPC has increased while conversion rate remains stable, the problem may be auction pressure.
If CPC is stable but conversion rate has fallen, the issue may be the landing page, offer, traffic quality, or website.
If conversions suddenly disappear entirely, you may have a tracking problem.
Strong PPC candidates show that they can work through these possibilities systematically.
Check Whether Tracking Is Actually Correct
Before concluding that performance has collapsed, confirm the data is reliable.
Ask:
- Are conversions still firing?
- Has the website changed?
- Has GTM been updated?
- Has a conversion action been removed?
- Did Consent Mode change?
- Has the CRM integration failed?
- Are duplicate conversions being recorded?
A campaign can appear to fail because measurement has broken.
If you've encountered this before, it's an excellent interview example because it demonstrates both PPC and analytics awareness.
Look at Search Terms
For Search campaigns, query quality is often important.
If CPA rises, investigate whether the campaign has started matching against:
- Lower-intent searches
- Informational queries
- Irrelevant terms
- Competitor traffic
- Broad categories
This can be particularly relevant when using broad match or automated campaign types.
A strong interview answer might explain how search-term analysis helped you identify wasted spend and tighten traffic quality.
Look at Auction Pressure
Sometimes the campaign hasn't fundamentally changed.
The market has.
You may see:
- Higher CPCs
- More competitors
- Increased impression share loss
- Aggressive competitor promotions
- Seasonal demand shifts
Auction Insights can help provide context.
If competition increased dramatically, simply trying to optimise your way back to last month's CPA may be unrealistic.
You may need to adjust expectations or strategy.
Check Conversion Rate
If traffic quality looks stable but conversions decline, investigate the website.
Potential issues include:
- Landing-page changes
- Slower site speed
- Form problems
- Mobile usability
- Pricing changes
- Stock availability
- Checkout errors
- Offer changes
This is where strong PPC professionals look beyond Google Ads.
Sometimes the correct recommendation is not another campaign optimisation.
It's fixing the website.
Lead Quality Can Reveal Hidden Underperformance
Lead generation campaigns can look successful inside Google Ads.
Imagine:
CPL falls from £70 to £45.
Looks great.
But Sales reports that the new leads rarely become customers.
The campaign has become more efficient at generating the wrong conversion.
This is an important type of underperformance to discuss.
You might explain:
"Platform CPL had improved, but CRM data showed the percentage of qualified leads had declined. We therefore shifted reporting towards cost per qualified lead and changed the conversion signals being sent back into Google Ads."
That demonstrates commercial thinking.
Don't Judge Performance on One Bad Day
Another useful point to demonstrate is that you understand volatility.
PPC performance moves.
One bad day doesn't necessarily justify a complete account restructure.
Consider:
- Conversion lag
- Normal daily variation
- Day-of-week patterns
- Seasonality
- Sample size
Good PPC professionals know when to intervene.
They also know when to wait.
But Don't Hide Behind the Learning Period Forever
The opposite problem can happen too.
Someone launches an automated bidding strategy.
Performance becomes terrible.
Three weeks later, they're still saying:
"It's learning."
Automation needs time.
But learning periods shouldn't become excuses for ignoring clear evidence.
A strong PPC professional knows how to balance patience with intervention.
Explain the Hypothesis You Tested
If you made changes, explain your reasoning.
For example:
"The initial diagnosis suggested that broad match was bringing in a larger share of lower-intent queries. We tightened negative keywords and separated the highest-value search themes so we could control budget more effectively."
Or:
"Conversion rate had fallen after the client redesigned the landing page, so we recommended testing the previous layout against the new version."
That shows a logical connection between the problem and the action.
Don't Describe Random Optimisations
Avoid giving an answer that sounds like this:
"I changed the bids, added negatives, rewrote the ads, adjusted locations, changed budgets, and rebuilt the campaign."
Why?
Because it sounds like you changed everything without understanding the cause.
An interviewer may reasonably ask:
Which change actually helped?
You probably won't know.
A better answer is structured.
Diagnosis first.
Hypothesis second.
Test third.
Result fourth.
Talk About What You Didn't Change
This can actually demonstrate discipline.
Perhaps one campaign was still profitable while another declined.
You might explain that you avoided restructuring the entire account because the evidence suggested the problem was isolated.
Knowing what not to touch is part of PPC management.
Be Honest If Your Fix Didn't Work
Sometimes your first solution fails.
That's fine.
For example:
"We initially tested a lower Target CPA because we wanted to restore efficiency, but conversion volume fell significantly. We reversed that change and instead focused on traffic quality and landing-page improvements."
That answer can be stronger than pretending you made one perfect decision.
It shows iteration.
Talk About Failed Tests Professionally
A failed test isn't necessarily wasted money.
Suppose you tested a new campaign structure and performance worsened.
What did you learn?
Maybe:
- The existing structure had stronger conversion density
- The new segmentation restricted Smart Bidding
- The audience behaved differently than expected
- The offer wasn't competitive
That learning can improve future decisions.
Explain When You Stopped a Campaign
Sometimes the best optimisation is turning something off.
If the evidence shows a campaign isn't commercially viable, continuing to spend purely because you've already invested money doesn't make sense.
You might say:
"After six weeks, the campaign remained significantly above the client's acceptable CPA despite multiple controlled tests. We concluded the economics weren't currently viable and moved the remaining budget into stronger-performing activity."
That's responsible budget management.
Demonstrate Commercial Awareness
Don't judge an underperforming campaign entirely on arbitrary PPC benchmarks.
A £100 CPA could be terrible for one business and excellent for another.
Ask:
- What is a customer worth?
- What margin does the business have?
- What is the lead-to-sale rate?
- What is the customer's lifetime value?
- What is the acceptable payback period?
This context determines whether the campaign is genuinely underperforming.
Sometimes Lower ROAS Isn't Failure
Imagine an ecommerce account moves from:
5x ROAS at £20,000 spend
to:
4.3x ROAS at £45,000 spend
Did performance get worse?
Efficiency declined.
But if 4.3x remains profitable, the business may now be generating significantly more revenue and profit.
Be careful when describing performance.
Commercial context matters.
Communicate Problems Early
Employers also want to know how you communicate when things go wrong.
If you're agency-side, don't wait until the monthly report to tell a client performance collapsed two weeks ago.
If you're in-house, don't wait for the Marketing Director to notice.
Explain:
- What happened
- What you know
- What you don't know yet
- What you're investigating
- What action you're taking
Strong communication builds trust even during poor performance.
Don't Overpromise Recovery
Imagine CPA rises by 40%.
Telling the client:
"Don't worry, I'll get it back down by Friday."
may sound confident.
It can also be unrealistic.
A stronger message would be:
"We've identified several likely contributors and are testing the highest-impact areas first. I'll monitor how those changes affect performance before recommending further action."
Confidence doesn't require pretending you control everything.
Prepare for the Question: "What Would You Do Differently?"
Most interviewers will eventually ask this.
Have an answer.
Maybe you would:
- Validate tracking earlier
- Test with a smaller budget
- Get more landing-page data first
- Set clearer commercial thresholds
- Introduce CRM feedback sooner
- Avoid changing several variables simultaneously
This is your opportunity to demonstrate learning.
Avoid Saying "Nothing"
If a campaign failed and your answer is:
"I wouldn't change anything."
you miss an opportunity.
Even if your original decision was reasonable, you can usually identify something you would improve in the process.
That could be better communication, clearer measurement, or earlier testing.
Don't Make Yourself the Hero of Every Story
Sometimes an underperforming campaign improves because multiple teams work together.
Maybe the PPC team fixed traffic quality.
The development team fixed the website.
Sales improved lead follow-up.
Be accurate about your contribution.
Saying:
"I identified the conversion-rate decline and worked with the CRO team to test the landing page."
is more credible than claiming you single-handedly transformed the entire business.
Use a Clear Interview Structure
A useful format is:
1. Objective
What was the campaign trying to achieve?
2. Problem
How did it underperform?
3. Diagnosis
What did you investigate?
4. Action
What did you change?
5. Result
What happened afterwards?
6. Learning
What would you take into future campaigns?
This keeps your answer focused.
Example Answer Structure
Imagine the interviewer asks:
"Tell me about a PPC campaign that didn't perform as expected."
You might explain:
"We launched a non-brand Search campaign for a B2B client targeting a CPA below £100. During the first month, CPA was closer to £160 and lead quality was weaker than expected.
I reviewed search terms, conversion rates, device performance, and CRM feedback. We found that broad match was driving substantial traffic from research-led queries that were technically relevant but rarely became qualified opportunities.
I expanded the negative keyword strategy, separated the highest-intent themes, and worked with the client to feed qualified lead data back into reporting. Over the following two months, cost per qualified lead improved by around 28%.
The main lesson was that optimising towards form submissions wasn't enough. We needed to connect campaign performance to sales quality much earlier."
That's a strong interview answer.
The campaign underperformed.
But the story demonstrates:
Analysis.
Ownership.
Commercial awareness.
Problem-solving.
Learning.
If the Campaign Never Recovered
That's okay too.
Not every story needs a happy ending.
Maybe the campaign ultimately remained unprofitable.
You can still explain:
"Despite improving CTR and conversion rate, the CPC required to compete on the core terms meant acquisition costs remained above the client's profitability threshold. We recommended stopping the campaign and reallocating budget."
That's a valid result.
You protected the client's money.
If the Underperformance Was Your Mistake
Own it.
Suppose you changed a bidding target too aggressively and conversion volume dropped.
You can say:
"I reduced the Target CPA too quickly, which restricted delivery more than I expected. Once I identified the impact, I reversed the change and adopted a more gradual approach. It taught me to be more cautious about making aggressive bidding changes without allowing enough room for the algorithm to adjust."
That's far better than trying to disguise the mistake.
What Employers Are Really Assessing
When interviewers ask about poor performance, they're often testing more than PPC knowledge.
They're looking at:
- Accountability
- Analytical thinking
- Resilience
- Communication
- Commercial judgement
- Decision-making
- Self-awareness
They want to know what you're like when the dashboard isn't green.
That's important because no PPC account stays perfect forever.
Don't Memorise a Perfect Script
Prepare your example.
Know your numbers.
Know the sequence of events.
But don't memorise every sentence.
You want the answer to sound like your real experience rather than a rehearsed case study.
Be ready for follow-up questions such as:
Why did you choose that solution?
What else did you investigate?
How did the client react?
How long did you wait?
What would you do differently now?
If you genuinely understand your example, those questions should be manageable.
Prepare More Than One Underperformance Story
Ideally, have a few different examples.
For instance:
Technical problem: Tracking failure.
Performance problem: CPA increase.
Commercial problem: Cheap leads but low quality.
Testing problem: New campaign structure performed worse.
That gives you flexibility depending on the interviewer's question.
The Bottom Line
You don't need a perfect PPC track record to perform well in a job interview.
You need to demonstrate that you know what to do when performance isn't perfect.
Don't hide underperforming campaigns.
Use them to show how you think.
Explain the objective.
Show the numbers.
Diagnose the problem logically.
Explain your actions.
Be clear about what worked and what didn't.
Own mistakes where appropriate.
And most importantly, explain what you learned.
Because employers aren't hiring PPC professionals on the assumption that every campaign will succeed.
They're hiring people they can trust when one doesn't.
If you're preparing for your next move in paid search, explore the latest PPC and Paid Media opportunities at Paid Media Jobs UK.