[LoganDark]

That's the metric I usually use. It's absolutely inconclusive, but it works for peace of mind at least. Have I seen any ads for something I bought? Usually the answer is "no". I'm still at the mercy of sort order on sites like Amazon and eBay, but that's much less scary because if I really care, I can sort by lowest price first.

[Buttons840]

By my own moral compass. If a company says "lots of people on Amazon are looking to buy what we have, let's make sure we're present in that market", that's completely moral. Compare that with, "a child is preparing for their math test tomorrow by watching a video, let's interrupt them and make them watch a commercial about our sugary, addictive, and unhealthy drink".