IN THIS ARTICLE
Separate brand demandFeed-only groupsScripts & placementsCustom labelsAudience signalsBidding & budgetsGoogle pitches Performance Max as an autonomous, cross-channel growth engine. In practice, its defaults often claim branded demand and burn budget on cheap app and kids’ YouTube inventory.
Discussions across communities like r/PPC show a consistent consensus: running PMax successfully requires strict guardrails that force the algorithm to hunt for genuine incremental revenue. Here is how experienced practitioners audit, segment, and constrain Performance Max.
01
Separate Brand Demand from PMax
The most common flaw is brand cannibalization. Without explicit blocks, PMax bids on the business name, reports artificially high ROAS, and starves generic prospecting searches.
ACTIONABLE STEPS
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Apply Brand Exclusions: Create a brand list covering your company name, common misspellings, and parent or subsidiary entities.
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Add Account-Level Negative Keywords: Catch leaked variations with an account list or request campaign-level negatives directly.
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Keep Standard Brand Search Active: Use exact match terms and low-cost bidding so brand data stays isolated from PMax.
02
Test Feed-Only Asset Groups for E-Commerce
Supplying full creative opens Search, YouTube, Display, Discover, and Gmail—often producing weak auto-generated video and spam display clicks. The long-standing Feed-Only, or Asset-Lite, tactic strips PMax back to modern Smart Shopping.
The feed-only recipe
Create an asset group containing only the Merchant Center product feed. Leave headlines, descriptions, images, and videos empty. Turn off “Final URL expansion.” This concentrates delivery on Shopping and high-intent Search.
03
Pull Back the Curtain with Scripts and Placement Audits
PMax hides placement detail in the primary UI. Media buyers rely on scripts and sub-reports to understand where spend flows.
Shopping
Video (YouTube)
Other: Display, Discover, Search, Gmail
Use Mike Rhodes’ PMax Spend Allocation Script. If 30%–40% of daily budget lands in Other or Video while conversions stay flat, the campaign is likely leaking cash.
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Exclude Mobile App Placements: Tools & Settings > Placement Exclusion Lists; block all 140+ app categories or apply the list through Google Ads Editor.
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Audit PMax placements: Reports > Predefined reports > Other > Performance Max placements; spot junk domains and exclude them account-wide.
04
Segment Inventory Using Custom Labels
A single catalog campaign lets high-volume, low-margin products dominate. Structure asset groups or campaigns around Merchant Center custom labels.
MARGIN-BASED
High Margin (>50%) vs. Low Margin (<20%)
Aggressive ROAS on low margins; lenient ROAS on high-margin winners.
PERFORMANCE TIERS
Top Sellers vs. Average vs. Underperformers
Prevent bestsellers from hogging 90% of budget.
ZOMBIE PRODUCTS
Products with 0 impressions in 30 days
Move inactive SKUs into low-tROAS or Maximize Clicks to force testing.
05
Treat Audience Signals and Search Themes as Hints, Not Targets
Audience signals are suggestions, not hard boundaries. Start with customer match lists—buyers from the last 90–180 days and high-LTV segments—before generic affinity categories.
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Search Themes: Add up to 25 per asset group, then monitor Search Term Insights to verify relevant intent instead of broad, off-topic matches.
06
Rules for Bidding and Budget Tweaks
PMax is sensitive to abrupt changes. Sudden shifts can reset the bid strategy into an extended learning phase.
10–15%
Adjust budgets or target ROAS/CPA by no more than this every 4–7 days.
6 DAYS
If conversion lag averages six days, let that full window clear before evaluation.
tROAS ↑
If spend runs hot, raise target ROAS slightly instead of halving the budget.
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PMax is not set-and-forget automation. It is a powerful auction engine whose outcomes depend on the constraints, signals, and economics media buyers give it.
