A lot of complaints from people who actually haven't seen the movie?

I'm just wondering because it seems like a lot of the negative posts on the board come from people who've just seen the trailer. It's perfectly reasonable if you saw the film and hated it, to each his own. But then you have posts like, "Premarital sex is wrong", "The genre is so played out", or "Another stupid film with *beep* friends". It just seems like people are trying to make a point or drive an agenda then actually talking about the movie.