When you run Performance Max for competitor conquest, as in the three-campaign B2B setup, it works your competitors' orbit across all of Google. That reach is the point. It's also the problem: PMax serves on mobile app inventory, and in-app banners and interstitials generate a steady stream of accidental clicks. For a B2B account, that's budget pouring into games, live-score apps, and resale marketplaces, none of which is ever going to become a pipeline.
Layer 1: exclude the off-ICP app categories
The first pass is blunt and fast. In account-level content suitability settings, exclude the app categories that could never be your buyer, games, dating, kids and family, and the rest of the consumer grab-bag. It's a category-level cut, so it isn't precise, but it stops the worst of the bleed on day one. One important limit: PMax ignores campaign-level placement exclusions and only respects account-level and MCC-level ones, so this has to be set at the account, not the campaign.
Layer 2: work the placement report
Category exclusions won't catch everything, and this is the part most people skip. Open the "Where ads showed" placement report (under Insights and reports) weekly and look at the actual apps your ads served on. On a B2B account it's a depressingly familiar list: a soccer live-scores app, a secondhand-marketplace app, a puzzle game. Select them and exclude from account. Then do it again next week.
These are close cousins of negative keywords: both are how you stop an automated system from spending on the wrong thing. The difference is that placements never fully stop appearing, so the work never fully ends.
Make it a habit, not a toggle
The mistake isn't running PMax for competitors, it works, and it's where some of your highest-intent traffic hides. The mistake is running it unsupervised. Set the category exclusions once, then put a recurring 15-minute placement review on the calendar. That single habit is the difference between PMax being a conquest engine and PMax being a donation to the mobile games industry.
The takeaways
- PMax serves on mobile apps, where accidental clicks quietly drain B2B budget.
- Layer 1: exclude off-ICP app categories in account-level content suitability settings.
- Layer 2: review the "Where ads showed" report weekly and exclude the specific apps that served.
- PMax respects account and MCC-level exclusions only, never campaign-level.
- Treat placement hygiene as a recurring habit, not a one-time setting.
Common questions
Why does Performance Max waste budget on mobile apps?
PMax serves across Google's inventory, including mobile app placements on the Display network. In-app banners and interstitials generate accidental clicks that rarely convert for a B2B advertiser, so budget leaks onto games and consumer apps that have nothing to do with your buyer.
How do you exclude mobile apps from Performance Max?
In two layers. First, exclude off-ICP app categories up front through account-level placement exclusions in content suitability settings. Second, review the "Where ads showed" placement report regularly and exclude the specific apps that actually served. PMax respects account-level and MCC-level exclusions.
Can you exclude placements at the campaign level in Performance Max?
No. Campaign-level placement exclusions are not available for Performance Max. PMax respects account-level and manager-account (MCC) level placement exclusions, so exclusions must be applied at the account level.