5. Prog Rock Fanboys
My favorite thing about progressive rock fanboys is the fact that they think they're smarter than the average music fan because they listen to this unlistenable bullshit. The rest of the world "doesn't get it". Unfortunately, we do "get it", your music is pretentious crap. Just because a band knows a lot of music theory and can play in odd time signatures or change time signatures quickly doesn't mean they know the first goddamn thing about writing a memorable song. In fact much of this crap doesn't have much melody in it at all, preferring to use the progressive elements to mask the fact that they can't write enjoyable music for shit. There are some decent progressive rock/metal bands out there, unfortunately there's a bunch of shit out there too. But if you don't like the music, the fanboys WILL let you know just how stupid they think you are.
THE MUSIC: I'm not sure The Mars Volta actually knows what a song is. Coheed and Cambria sound like what would happen if someone threw an emo band and a prog rock band into a blender, drank it, and then shit it out. Yes, they ARE that bad.
4. Teeny Boppers
Only rating this low because I no longer work at Target or see them that often, otherwise they may contend for #1. Teeny boppers are better known as the gaggle of shrieking pre-pubescent girls at the nearest Jonas Brothers atrocity, crying and screaming and falling all over themselves and their musically-challenged idols. In the eyes of a teeny bopper, their idols are absolutely infallible, their music the absolute best in history, no matter how objectively horrendous it actually may be. The music is ultimately disposable, probably never to be remembered after five years. However, the teeny bopper will claim they will love it forever, after several years it may gain a nostalgia factor, but litte else redeeming it. Just look at the New Kids on the Block for proof.
THE MUSIC: Whatever horrible little boy band is currently popular.
3. Indie Fans
The major thing to remember is that they listen to horrible shit that you have never heard of. Be glad for that. They hate everything you have heard of and will namedrop bands that no one in their right mind has heard of or would listen to. The more obscure the better. Indie fans are well known for their fickle attitudes toward music. The minute one of their favorite groups becomes popular, they WILL stop listening. There are a few exceptions, bands who never leave the collection of the indie fan. Their music taste is unimpeachable and they will backtrack if you call them on their fickle nature.
THE MUSIC: Constantly changing crap that they play on those college radio stations that normal people avoid like the plague. Radiohead is the standard by which all other loser crap is measured.
Oh god, do I hate emos. Thankfully this trend SHOULD be coming to an end soon. I suppose there's more to being an emo than wearing girls jeans, haircuts that look like they stuck a fork into a toaster, outrageously elaborate Myspace profiles, feeling depressed and cutting themselves, and the patently offensive music...what am I saying? There really isn't. Emos are histrionic attention whores who listen to terrible music.
THE MUSIC: Most bands identified as being emo nowadays claim that they were never emo in the first place, thus abandoning their psychologically fragile fanbase. Good for them, but still, go the fuck away.
What's worse than an emo? A juggalo. Seriously, there is a movement of fans centered around the absolute worse pile of horseshit music to ever sprout legs and crawl out of the primordial ooze that is "pop music", Insane Clown Posse. Completely emotionally stunted and intellectually retarded, these jackasses will jump to the defensive if anyone says anything slightly demeaning towards "the family" or their godawful shit music. I'm expecting a few death threats just from writing this. Seriously, look up "juggalo" on youtube.
THE MUSIC: As mentioned before, Insane Clown Posse. Yes, an entire sub"culture" of fans derived from one horrible band that features a couple of asshats in clown makeup.
(DIS)HONORABLE MENTION: Suburban white kids who listen to and center their life around rap music. See: Malibu's Most Wanted, or don't, I don't give a fuck.