How to Spot Hidden Spend in Performance Max

If your Performance Max campaigns are “working” — but ROAS still isn’t where it should be — you’re not alone.

Many brands see healthy-looking top-line numbers… until they dig deeper. That’s when they find it: hidden spend in low-quality placements dragging down efficiency.

Performance Max is a black box by design. But that doesn’t mean you’re powerless. We’ve built a simple but effective framework to identify hidden waste — and systematically exclude it without breaking the whole machine.

What “Hidden Spend” Actually Means

When we say “hidden spend,” we’re talking about budget quietly going toward:

• Low-intent Display placements (mobile games, clickbait content farms, app banners)

• Search partner sites that don’t convert

• Auto-play YouTube placements that inflate views but drive zero action

• Spammy app placements with high misclick rates

These don’t show up obviously in the PMax dashboard. Google doesn’t want you to panic. But if you’re scaling aggressively — or testing new segments — these placements can quietly siphon thousands in spend with little to no return.

Our Framework for Identifying Hidden Spend

We use a 3-step process to surface waste and steer PMax campaigns back toward high-value placements.

Step 1: Audit Signals in GA4 and UTM Layers

Start by looking outside of Google Ads.

In Google Analytics 4, dig into:

• Source/Medium: Look for unexpected referral sources

• Landing Pages: Check for spikes from unusual pages

• Engagement Time: Low time-on-site or high bounce = bad placements

If you’re using UTMs correctly on your campaigns, you’ll start spotting red flags — especially from Display or video placements that don’t match buyer intent.

Step 2: Pull a Placement Report (the Hacky Way)

Even though PMax hides most placements, you can sometimes extract a rough list using:

• GA4 Event Paths

• Third-party tools like Triple Whale or Northbeam (if integrated with Google Ads)

• The Ad Preview & Diagnosis tool (for real-time placement previews)

You won’t get the full picture, but these fragments help you piece together which placements are underperforming.

Step 3: Layer in Account-Level Exclusions

Once you’ve identified low-value placements or patterns, start building out exclusion rules:

• Add categories of mobile apps or websites to your account-level exclusions

• Create negative keyword lists if search partners are bleeding spend

• Use IP exclusions for suspicious traffic from bot-heavy zones (advanced)

While you can’t isolate specific placements inside PMax, account-level rules still apply globally — and over time, they shift the traffic mix in your favor.

Bonus: Preemptive Signals to Watch For

If you want to stay ahead of the waste instead of reacting to it, build these habits:

• Set ROAS thresholds at the asset group level, and monitor trends weekly

• Watch your engagement metrics in GA4 (especially time-on-page and scroll depth)

• Compare click-assisted vs. view-through conversions to spot inflated Display metrics

• Use branded search as a pulse check — if PMax is driving conversions but your branded search spikes, attribution might be masking real efficiency issues

Why This Matters (More Than You Think)

The difference between a 2.0 and 3.0 ROAS in PMax often isn’t creative or bid strategy — it’s waste. If you can reduce Display leakage by just 10–15%, and reallocate that spend into Shopping or high-intent YouTube — you unlock more revenue without spending more. Most brands scale by increasing their budget. We scale by cleaning the pipes first.

Final Thoughts

Performance Max doesn’t want you looking under the hood. But that’s exactly where the levers are. Once you know what to look for — and where to trim the fat — you can turn PMax into a real growth engine, not just a black box you feed budget into.

Takeaway:
Smart buyers don’t just launch campaigns. They interrogate them — and remove what doesn’t drive results.