Not a great deal, to be honest … but they do share one key similarity.
If you ever watched The Big Short (or read the book) or otherwise studied the GFC, you’ll remember how a major part of the crisis was caused by financial institutions blending lower-quality, much riskier subprime loans with higher-quality, lower-risk ones. This created mortgage-backed securities that looked safer than they really were.
In The Big Short, this concept is humorously illustrated using the analogy of a restaurant combining old, waste fish with fresh ingredients to create a dish that appears high quality—even though it’s mostly made from stuff you wouldn’t feed your dog.
This allowed financial institutions to hide the true nature of the "product" being sold. Everyone seemed like a winner … until the whole thing collapsed.
With Google Ads Performance Max, a similar principle is at play. Google can generate impressive headline numbers—like ROAS, conversion rates, or cost per conversion—partly through branded ads and retargeting that you may not realize is included (i.e. paying Google for customers who were quite possibly going to buy from you anyway)
Because the system is relatively opaque, unless you dig into it, you might not see how it works.
What’s more, Google can blend this "premium" performance-generating activity with junk inventory from its network, like ads on low-quality display sites, irrelevant video placements, or poorly matched search keywords. These are things you’d probably avoid if you had more control ... but chances are you don't even know they are happening.
When the junk is blended in with the good stuff, you might think you’re getting a great deal if you just look at the headline figures—especially when Google takes credit for conversions that might’ve happened anyway from customers already intending to buy.