CTR is not a bad metric. It's used in a bad environment.
Every few months, the same take comes back: "Stop optimizing for CTR." "CTR doesn't measure real performance." "Clicks don't equal outcomes."
I get it. And I've seen the data that supports those arguments. But I think the conversation is missing something important.
CTR gets blamed a lot. But what I usually see when I dig into campaigns where CTR "doesn't work" is that the inventory underneath it is a mess. That's the actual issue.
Think about walled gardens for a second - i.e Meta, Google, Amazon. CTR in those environments is a legitimate signal. You're reaching real people, on real platforms, with relatively controlled inventory. When someone clicks, there's a high probability that an actual human made a decision to engage with your ad.
Now compare that to the open web. You're dealing with MFA sites inflating impressions, bot traffic generating fake clicks, misplaced ads that get accidental taps, and inventory that was never meant to be seen by a real person. In that environment, CTR becomes noise.
When I hear "CTR is useless," what I actually hear is "I haven't done the work to clean up my supply path." And that's a very different conversation.
If you run a campaign on curated, high-quality inventory - real publishers, verified traffic, proper ad placements - CTR suddenly becomes useful again. It tells you something real about creative resonance and audience interest.
But if your campaign is running across thousands of unknown domains with no supply quality controls, then yes - CTR is meaningless. So is every other engagement metric you're looking at.
What to do about it?
Before dismissing CTR, audit your supply path. Run inventory quality reports. Check domain-level performance. If 30-40% of your impressions are going to MFA or low-quality sites, no engagement metric will be reliable - not just CTR.
Use CTR as a signal in controlled environments. Walled gardens, curated PMPs, allowlisted publishers - in those contexts, CTR gives you real feedback on creative and audience fit.
Layer it with other signals. CTR alone doesn't tell the full story. But CTR combined with viewability, attention metrics, and conversion data in a clean environment gives you a much clearer picture.
The industry loves to debate whether metrics are "good" or "bad." But most metrics work fine - when the underlying data is clean.