so you're saying facebook couldn't scan the pictures people post up, see that a user's finger is not painted properly, and thus start displaying the appropriate ads?
If I'm sitting in a restaurant having a conversation with a friend and a person from the next table leans over and interrupts to say "I notice your nails aren't painted properly, can I interest you in our new line of nail varnish?" then my first thought will be something like wouldn't it be cool if something horrible and painful happened to this person. Even if I was considering trying a new line of nail varnish. That's what targeted facebook ads feel like.
Is it though? Because I always thought it felt more like a used car salesman crossed with clippy.
"I see you're trying to paint your nails, would you like to buy some nailpolish for that?"
"Hey so last time I saw you you talked about nail polish, I've got a friend selling some... Did you want cheap tickets to a nail-painting seminar? There's a nail & manicure kit on Amazon!"
Only it wasn't even you at the party, it was your friend that did one Google search for nail polish months ago and now you're forever The Nail Polish Guy.
You can control what kind of data Google is allowed to collect about you from Google's settings dashboard : https://www.google.com/settings/dashboard
I just always found it really annoying when I'd spend a couple of days researching a purchase, and then for the next month I was getting ads for the thing I'd just bought. I don't need one of those any more, I've got one!
I call these adds "stalker ads" to convey this very feeling, and it certainly isn't limited to just Facebook.
Your insecurities analysed and used against you in real time.
if there's a way to make money off someone's insecurities legally, you can bet that it's gonna happen. I do worry, but i think worrying isn't going to stop it from becoming true.