Let's say in anime...
Naruto, Bleach, One Piece and the likes are the example of mainstream anime. One of the reasons is that they are becoming overrated because of the "fags," those who have few knowledge about anime's, saying that it is the best anime ever.

Another example is Sword Art Online. It was supposed to be a good anime, but it turned out to be an overrated anime because of the fags, making the otakus (people who has much knowledge about anime's, manga's,  and the likes) don't want to watch it anymore.

So basically, fags turn some animes into mainstream anime's, and otakus dislike mainstream anime.

~Yuuhi