Facebook could sell less invasive adds targeting without selling you. E.g. based on groups. E.g. if I join group called "cat lovers", they could show me cat rel

Facebook could sell less invasive adds targeting without selling you. E.g. based on groups. E.g. if I join group called "cat lovers", they could show me cat related adds when I go to that group page, or if my current visible stream has that groups' posts. But what they actually do is they package me as sellable with all my private info and perhaps whatever I have written ever or any sites I have visited.