My first reaction though was abhorrence, and a refusal to ever deal with the company using that ad- retargeting. The practice feels like something a really scummy sly used car salesman would use.

I don't think you realize how many companies you've decided to not do business with.

>The practice feels like something a really scummy sly used car salesman would use.

How different is it from walking into Home Depot and talking with a salesperson about paints to touch up the home you're about to put on the market. Then, upon return a month later, that same salesperson recognizes you, inquires as to your new home and mentions a deal they're running on Sherwin Williams paint?

It's also a social interaction. If the sales person did that of their own volition, then I'd react positively.

However, I'd be less responsive if the information had been retrieved via, say, facial recognition in some way.

The difference is that one case is someone (or a business) wanting to help and improve my life -- and, yes, to sell me something. The other is someone wanting to ell me something.

I think you're being overly generous in the case of the former. The person's livelihood depends on selling you something. She or he is just wrapping it in a social patina that will prevent your "I'm being sold something" warning lights from going off.