Most Google Ads accounts I audit have money walking out the door. Not because the campaigns are fundamentally broken, but because of a handful of mistakes that quietly compound over weeks and months. The kind of things that don't look dramatic in a weekly check-in but add up to thousands over a quarter.
I'd estimate 20-30% of spend in an average unmanaged account goes to waste. That lines up with what I see in practice, and with broader industry data - a 2025 GrowthSpree study of 43 enterprise B2B accounts found 36.1% of total spend going to clicks that never had a chance of converting. That was $11.3 million across $31.2 million in total spend.
Here are the five mistakes I see most often, with real fixes you can apply this week.
1. Not Reviewing Your Search Terms (The Biggest Google Ads Budget Killer)
This is still the number one source of wasted spend in every account I take over. With broad match getting broader and Google's matching algorithms expanding every year, the gap between what you bid on and what you actually show up for keeps growing.
I picked up a client last year spending $5,000 a month on campaigns for a commercial cleaning business. Their broad match keyword 'office cleaning' was triggering ads for 'cleaning games for kids', 'office cleaning jobs near me', and 'how to clean office chair wheels'. Over $800 gone in a single month on searches that would never turn into a lead.
That's a dramatic example, but every account has a version of it. The GrowthSpree report found $4.87 million wasted on irrelevant search terms across the accounts they studied, with 62,964 clicks on terms like 'surveys' producing zero conversions.
What to do about it:
- Check your search term report weekly for new accounts or recently added keywords. For established accounts, fortnightly is fine.
- Sort by cost (highest first) and look for anything that doesn't match buying intent - job searches, informational queries, wrong location, wrong industry.
- Add negatives in batches. Don't just add the specific bad term - add the root word that's causing the problem. If you're seeing 'office cleaning jobs', add 'jobs' as a negative, not just the full phrase.
- I've written a full guide on this: How to Read Your Google Ads Search Term Report.
My take: negative keywords aren't a set-and-forget exercise. They're ongoing maintenance, like mowing the lawn. Skip a few weeks and the mess compounds fast.
2. Letting Google Auto-Apply Recommendations
This one makes me twitch. Google's auto-applied recommendations are turned on by default in many accounts, and they can make changes to your campaigns without your knowledge or approval. New keywords get added. Match types get expanded to broad. Bid strategies get switched. Budgets get adjusted.
Brad Geddes from Adalysis - someone who's spent decades in this space and analysed data across thousands of accounts - put it plainly in a Search Engine Land article: 'I've seen Google's auto-apply settings wreck accounts before.'
And it's not just recommendations. In February 2026, Search Engine Land reported that Google's 'low activity system bulk changes' tool was automatically re-enabling paused keywords - something advertisers hadn't consented to and Google hadn't announced. Performance marketing consultant Francesco Cifardi was among the first to flag it publicly.
What to do about it:
- Go to Settings > Auto-applied recommendations and turn off everything. Right now. I'll wait.
- While you're there, check Settings > Ad Suggestions and set it to 'Don't automatically apply ad suggestions'.
- Set a calendar reminder to check these settings monthly. Google has a habit of quietly re-enabling things after platform updates.
- Review the Recommendations tab manually. Some suggestions are genuinely useful - but you should be the one deciding which ones to apply.
Take it from someone who's opened an account to find Google had helpfully added 200 broad match keywords overnight - check these settings first, ask questions later.
3. Ignoring Where and When Your Ads Show
This one sounds basic, and it is. But it explains hundreds or thousands in wasted spend more often than you'd think.
I see this constantly: ads running 24/7 for a business that takes phone calls during office hours. Ads showing in regions the business doesn't serve. Desktop campaigns burning budget when all the conversions come from mobile, or vice versa.
The GrowthSpree data backs this up. Across 43 B2B accounts, 67.8% of off-hours spend (think 3am clicks) generated zero conversions. Weekend spend was even worse - conversion rates dropped from 2.7% on weekdays to 0.8% on weekends, wasting $2.97 million in their dataset.
Sam Tomlinson, who writes one of the best PPC newsletters around (The Digital Download), puts it well: 'It does not make sense to run ads saying "call now" when the call centre is closed. It does not make sense to run ads for a service business in an area that the business does not serve. Is it basic? Yes. Does it often explain hundreds - or thousands, or sometimes millions - in wasted spend? Also yes.'
What to do about it:
- Run a day-of-week and hour-of-day report. Look at conversion rates and cost per conversion, not just clicks. If Sunday at 2am has never converted, you don't need to be there.
- Check your location targeting. Make sure you're targeting people 'in' your target locations, not just people 'interested in' them (Google's default is the broader option).
- Review your device performance. If mobile converts at half the rate of desktop, set a negative bid adjustment or split into separate campaigns.
- For B2B accounts specifically: unless you have strong evidence otherwise, consider pausing outside business hours. The data consistently shows off-hours B2B clicks are mostly waste.
4. Running Campaigns Without Proper Conversion Tracking
If you're optimising your campaigns without accurate conversion data, you're steering blind. And Google's Smart Bidding algorithms are steering blind right alongside you - they optimise towards whatever you tell them is a conversion, so if that data is wrong, the algorithm enthusiastically spends your budget chasing the wrong signals.
The most common mistakes I see:
- Counting every conversion instead of one: If your goal is lead generation and counting is set to 'every', someone refreshing your thank-you page counts as multiple leads. Your reports look great. Your actual pipeline doesn't.
- Tracking the wrong actions: Page views, button clicks, or time-on-site set up as conversion actions. I've seen accounts with a 40% 'conversion rate' where actual form fills were under 3%. Smart Bidding was optimising for cheap, meaningless actions.
- No conversion tracking at all: Sounds extreme, but I still see it. An account spending $3,000-$5,000 a month with no conversion actions set up, running on maximise clicks. Every dollar is a guess.
This doesn't just waste the obvious spend - it corrupts your bidding. When Smart Bidding has bad data, it learns the wrong patterns and actively seeks out more of what isn't working.
What to do about it:
- Audit your conversion actions. Go to Goals > Conversions > Summary and check what's actually being counted. Remove or set to 'secondary' anything that isn't a genuine business outcome (purchase, qualified lead, phone call).
- Set lead gen conversions to count 'one' conversion per click, not 'every'.
- If you're running lead gen on Smart Bidding, seriously consider feeding offline conversion data back to Google. It's the single best thing you can do for lead quality.
- Test your tracking. Submit a test form, make a test purchase, call your own tracking number. Do this quarterly at minimum.
5. Setting Budgets Evenly and Forgetting Them
This is the one nobody talks about, and it might be the most expensive mistake on this list.
Most accounts I audit have budgets split roughly evenly across campaigns - $50/day here, $50/day there - regardless of how each campaign is actually performing. The high-performing campaign with a $30 CPA against a $100 target is capped at the same budget as the underperformer sitting at $140 CPA.
Sam Tomlinson shared a case study in his newsletter of a brand spending $300,000 per month with budget split evenly across Google, Meta, and Programmatic. When he dug into the Google account, the non-branded search campaign had a $60 CPA against a $100 target - and was budget-capped. Meanwhile, the competitor campaign was running at $140 CPA, still burning through its full daily budget. His estimate: the account would perform 20-30% better just from reallocation, without changing a single keyword, ad, or landing page.
That's a big account, but the principle applies at every level. If you're spending $3,000 a month and one campaign is generating leads at half the cost of another, feeding more budget to the winner and pulling back on the loser is the fastest return on your time.
What to do about it:
- Review campaign-level cost per conversion weekly. If one campaign consistently delivers cheaper conversions, it should get more budget - not the same as everything else.
- Check for 'Limited by budget' status on your campaigns. If your best performer is capped, that's money left on the table.
- Don't set monthly budgets and walk away. Performance shifts week to week. A quick five-minute budget rebalance every Monday morning can make a meaningful difference.
- My take: most advertisers would get more from reallocating existing budget than from spending more. Fix the distribution before you increase the total.
Key Takeaways
- Check your search term report regularly and add negative keywords - this alone can recover 20-30% of wasted spend in neglected accounts.
- Turn off all auto-applied recommendations and ad suggestions. Review them manually.
- Audit your location, schedule, and device targeting against your actual conversion data. Cut the times and places that don't convert.
- Make sure your conversion tracking is accurate and tracking real business outcomes. Bad data corrupts Smart Bidding.
- Reallocate budget from underperforming campaigns to your winners. Even budgets across campaigns is almost never the right approach.
None of these are complicated. The issue is that most accounts set them up once and never revisit. A 30-minute audit covering these five areas can surface thousands in annual savings - and you don't need to be a PPC expert to do it.
If your Google Ads account hasn't had a proper review in a while and you'd rather someone else dig through the data, that's what I do. Happy to take a look.