I think this actually already happens (at least the criteria part) for Facebook ads. I just went to Facebook and went to the "..." menu for one of the ads that

I think this actually already happens (at least the criteria part) for Facebook ads. I just went to Facebook and went to the "..." menu for one of the ads that showed up and clicked "Why am I seeing this?". It said this: "You're seeing this ad because Freshly wants to reach people ages 18 and older who live or were recently in California. This is information based on your Facebook profile and where you've connected to the internet." So my impression is that Facebook already allows you to see the exact targeting criteria that went into any ad that shows up. Maybe if this was more prominent, especially in cases where the filter seems suspiciously like microtargeting, the trick wouldn't have worked.