Glee is decent, cept when the song shit comes in, i just skip that.
Bieber is hated mainly because of his annoying 8 - 16 year old fanbase.
One direction, see above.
Twilight is just bad. Seen the movies, never again.

Of course people assume something is shit when everyone else tells them it's shit. When nobody is telling you something is good or has any good qualities there isn't much reason to believe that it's good.
People hate Twilight because it's literally the wet dream of a 30 year old Mormon woman and the books themselves are dreadfully boring while the movies are horribly written with shitty characters.
People hate Justine Beiber because every song he makes seems to be the same thing, falling in love with a random girl. He only appeals to preteen girls/ gay preteen boys. He is a dime a dozen singer that will be replaced by someone else within the next two years because nothing he makes stands out from the sea of other pop singers/songs out there.
Never head of One Direction.
Never watched Glee because the clips I've seen of the show are really boring or just not entertaining to me.

No, quite often, people hate a thing because others do. Not saying everyone does, but quite a few do.

And those people are called bandwagon faggots.

Yes, and they all smell of burnt yogurt and toe jam