Funny how Facebook can have all of this information about me, my preferences, my social groups, etc., and has not once served me a remotely relevant advertisement.
Even worse are the socially slip-streamed ones that started as a Sponsored post in a friend's news feed that they found funny/interesting/whatever and re-shared. Once reshared it loses even that gray, barely there "Sponsored" tag and has "grown up into a real boy" in the news feed.
A lot of the mind games in the last election cycle happened because of that (target ads to people susceptible to reshare them and watch them go viral for relatively cheap). Facebook has said they may try to crack down on that sort of thing, but slip-streaming ads is where they make their most money and they don't have enough financial incentive to really fix that.