So in a world where targeted ads are actually useful you would probably opt-in? Would you ever try something like this?

You'd take a survey about your interests and/or things you're in the market for then you would get a monthly email with a variety of targeted ads. Over a year ago I wrote down in my "ideas" notebook "privacy respecting opt-in email advertisements" but then when I looked at it again later on I thought "I don't think anyone would sign up for this" haha.