Over the past two years we've audited dozens of Google Ads accounts for e-commerce stores and businesses. And you know what still surprises us? The same mistakes come back again and again. They're not exotic problems — they're the basics, the kind of thing you can fix in a few hours, yet they quietly burn thousands every single day until you do.
We made some of these mistakes ourselves early on. So we're writing this without a hint of superiority — think of it as a checklist to run through and see whether any of it applies to you. Because most businesses have at least one of these mistakes sitting in their account right now.
The short version, for anyone who doesn't have time to read it all
- Micro-conversions set as your primary conversion action = Smart Bidding optimises for newsletter sign-ups instead of purchases. A 5-minute fix with an immediate impact.
- Missing Enhanced Conversions = you're losing 15–30% of your conversion data. Smart Bidding is optimising on an incomplete picture.
- Too many small campaigns = the algorithm never has enough data in any of them. Consolidate into 3–4 campaigns.
- Auto-generated video in PMax = it damages your brand image. Upload your own video — 15 seconds is enough.
- Making changes during the Smart Bidding learning phase = you restart the learning from scratch. Hold off for 3–4 weeks.
- Never working with your search terms = you're paying for queries like "how to make" or "jobs in the industry." Clean them up weekly.
- A poor product feed = Google won't show your products for the right queries. The feed matters more than the campaigns.
- Brand and non-brand in the same campaign = distorted metrics. Branded traffic inflates ROAS and masks the real problems.
Mistake 1: Micro-conversions as your primary conversion action
This is by far the most widespread mistake — and the one with the fastest payoff once you fix it.
What's happening: In Google Ads you've set not just the purchase as a primary conversion, but also newsletter sign-ups, add-to-cart, key page views or clicks on your phone number. Smart Bidding then treats all of these as equal and optimises for the cheapest one — usually the newsletter.
Why it's a problem: The algorithm delivers 200 "conversions" a month, but 150 of them are newsletter sign-ups worth 15 CZK (≈ €0.60) each. You've actually got 50 real orders. Your CPA looks great, but the revenue doesn't match it.
The fix: Set only the purchase as your primary conversion. Mark everything else as secondary (observation only). It takes 5 minutes. You'll see the impact within two weeks.
Mistake 2: Missing Enhanced Conversions
Without Enhanced Conversions you're losing 15–30% of your conversion data. A user clicks an ad on their phone and buys on their laptop — and Google never connects the two. Smart Bidding then optimises on an incomplete picture.
Why it's a problem: The algorithm can't "see" conversions that genuinely happened. Campaigns that are actually performing well look like underperformers. You might pause them or cut their budget based on bad data.
The fix: Turn on Enhanced Conversions — send a hashed email (ideally phone and address too) with each conversion. Median uplift: +5% conversions on Search, +17% on YouTube. Results within 2–4 weeks.
Mistake 3: Too many small campaigns
The classic scenario: an e-commerce store with 10 product categories runs 10 campaigns, each on a budget of 500 CZK (≈ €20) a day. The result? No campaign has enough data for Smart Bidding (you need 30+ conversions per campaign per month).
Why it's a problem: Smart Bidding is only as smart as the data it's fed. A campaign with 5 conversions a month sits in a permanent "semi-learning" state — the algorithm never truly learns.
The fix: Consolidate. Instead of 10 small campaigns, run 3–4 bigger ones. Branded Search, non-brand Search, Shopping/PMax. More data in one campaign = faster learning = better results.
Mistake 4: Auto-generated video in PMax
If you don't upload your own video to a PMax campaign, Google automatically builds one from your images and text. And the result looks exactly how you'd expect an auto-generated video to look — unprofessional.
Why it's a problem: This video represents your brand on YouTube, in Gmail and in Discover. And it looks like a PowerPoint deck from 2005. The PPC community is unanimous on this one — auto-generated video hurts your image.
The fix: Upload your own video. It doesn't have to be a Hollywood production — 15–30 seconds shot on a phone, with clean audio and a clear message, is enough. E-commerce stores that use their own video report 25–40% better campaign performance.
Mistake 5: Making changes during the Smart Bidding learning phase
Smart Bidding needs 3–4 weeks (roughly 50 conversion events) to learn. Any major change — budget, bidding strategy or targets — triggers a restart of that learning.
Why it's a problem: The typical scenario: you switch on Target ROAS on Monday. By Wednesday your CPA has jumped 40%. By Friday you've panicked and reverted it. The result: you've wasted a week of data and learned nothing. And every restart sends the algorithm back to square one.
The fix: Set it and leave it alone. A minimum of three weeks without changes. If the nerves get the better of you, set an automated alert at twice your target CPA — you've got a safety net without touching the campaign every day.
Mistake 6: Never working with your search terms
Even in the era of broad match and AI Max, you still need to regularly check which search queries you're paying for. Without maintaining your search terms, you end up paying for queries like "how to make a paper flower," "florist jobs" or "flowers wikipedia."
Why it's a problem: Every irrelevant click costs money. For a store with 100 clicks a day and 10% irrelevant queries (a conservative estimate), you can waste 3,000–5,000 CZK (≈ €120–200) a month. On larger accounts, far more.
The fix: Review your search terms report every week. Focus on n-grams — two-word combinations that keep showing up in non-converting queries. Add them as negative keywords. The first 30 minutes alone will save you thousands a month.
Mistake 7: A poor product feed
The feed decides whether your product shows up for the right search query in Shopping and PMax. And most e-commerce stores have a feed in a sorry state.
Typical problems:
- Product titles contain internal codes instead of what people actually search for ("NKS-2847-BL" instead of "Women's black leather boots")
- Missing attributes — colour, size, material, GTIN
- Low-quality images — blurry, badly cropped, watermarked
- Out-of-date prices or availability
Why it's a problem: Google matches products to queries based on the feed. A bad title = a bad match = your products show up for the wrong queries, or don't show up at all. No campaign setting will fix this.
The fix: Go through your feed and rewrite the titles to match how people actually search. Fill in the missing attributes. Replace the low-quality images. This is an investment that pays off across every campaign — Shopping, PMax and Demand Gen alike.
Mistake 8: Brand and non-brand in the same campaign
Branded traffic (people searching for your name) naturally has a low CPA and high ROAS. Non-branded traffic (people searching generic queries) is more expensive. If you keep them in the same campaign, the branded traffic inflates your average metrics and masks the problems in your non-brand.
Why it's a problem: You look at the report and see an 800% ROAS. Brilliant! Except 70% of those conversions are branded — you'd have won them without the ad anyway. Your non-brand campaigns are running at a 200% ROAS, but you can't see it because it's buried in the average.
The fix: Separate your branded and non-branded campaigns. Always. Run a dedicated brand campaign with its own budget and metrics. Judge non-brand on its own. In PMax, set brand exclusions.
How to work out what these mistakes are costing you
A simple walkthrough:
1. Open Google Ads → Tools → Conversions. How many primary conversion actions do you have? If more than one — mistake 1.
2. Check Enhanced Conversions → are they on? What's the match rate? If it's 0% or missing — mistake 2.
3. Count the campaigns with the same goal (Sales). More than 4–5? — mistake 3.
4. Open PMax → assets → video. Is it all auto-generated? — mistake 4.
5. Look at your change history for the past month. Did you change bidding/budget more than twice? — mistake 5.
6. Open the search terms report. When did you last add negative keywords? More than a month ago? — mistake 6.
7. Look at your Shopping feed → product titles. Do they contain what people actually search for? — mistake 7.
8. Look at your brand vs. non-brand split. Have you separated them? — mistake 8.
At LK Media this is the first thing we do with every new client. Most accounts have at least 3 of these 8 mistakes. Fixing them typically takes 1–2 days, and the impact shows within 2–4 weeks.
In closing
None of these mistakes is fatal, and every one of them is fixable. Some in 5 minutes (micro-conversions), some in a few hours (feed, tracking). But every day you leave them in place, they cost you money.
Run through the checklist above. If you find one or two mistakes, fix them. If you find more — consider an account audit with someone who knows where to look.
Want a free audit of your Google Ads account? Email info@lkmedia.cz — we'll go through your account and tell you exactly what to fix and how much it will save you.
Frequently Asked Questions About Google Ads
Which mistake costs the most money?
Micro-conversions set as your primary conversion action (mistake 1). Because it directly determines what Smart Bidding optimises for. If the algorithm is chasing newsletter sign-ups instead of orders, you're wasting your entire budget. And it takes 5 minutes to fix.
How quickly will I see improvement after fixing them?
It depends on the mistake. Micro-conversions and brand/non-brand separation: impact within 1–2 weeks. Enhanced Conversions: 2–4 weeks. Product feed: 1–2 weeks (once approved in Merchant Center). Campaign consolidation: 3–4 weeks (the learning phase for the new structure).
How many mistakes does a typical account have?
In our experience, 3–5. The most common combination: missing Enhanced Conversions + too many campaigns + no work on search terms. Together, those three can mean a 20–40% loss in budget efficiency.
Can I do the audit myself?
You can handle the basic check using the checklist in this article. But some issues (duplicate tracking, misconfigured Consent Mode, incorrect attribution) require technical know-how. If you find more than 2 mistakes, we recommend a professional audit.
How often should I check my account?
Search terms: weekly. Campaign performance and bidding: weekly (but don't change settings more often than every 2 weeks). Feed: monthly. Enhanced Conversions diagnostics: monthly. Full audit: quarterly.
