Facebook has always tried to act like it knows the lives of its users. This used to manifest itself in really helpful features--People You May Know and Recommended Pages, for example. Most recently, they began to personalize their advertisements, which is a really good idea on paper. The problem is that the service, when implemented, is a bit... single-minded.
I'm one of those lucky people who lives in a town where I can be at least 73% sure that putting my sexual orientation on my Facebook will not result in a congregation of devotees performing an exorcism outside my door. (Although, come to think of it, I do live three doors down from a church...) One night, after watching a really sappy frustrated-gay-men romcom my mom put in the Netflix queue for me as a teaching moment, I got up the courage to fill the "interested in" box on my Facebook profile. Either no one saw it or no one was surprised (I can't imagine why; I'm totally the motorcycle-riding football-watching boob and beer enthusiast type), but one thing did come of this: Facebook's advertising engine became that friend that always talks about the same thing.
The trouble is that Facebook's advertisements aren't always tactful, either. Of the ads I see, 3/4 of them roughly resemble these two:

Don't get me wrong, I understand their arithmetic.
Male + Interested in: Men + Single + Almost always online on Friday nights + Watches romantic comedies frequently enough to suggest desperation = Interest in dating services
They just don't have to be so accurate.
Then, sometimes, they just get offensive, like this one:

I mean, come on, Facebook. Really? Does it really look like that's a book I'd-- nevermind. Don't want to know the answer to that.