At a certain point, it became very cool to hate things that are popular. I have no idea when this started - I imagine that at some point, people were shitting all over Socrates, clowning him with remarks like, "My life is better unexamined and mysterious, gawd, loser." But in contemporary fashion, it seems to come up most often when discussing musical taste.
Specifically, I was at a party this weekend where some dude was all like, "Third Eye Blind sucks!" I took great offense, because I like Third Eye Blind, and also, it seems like a kind of random band to attribute sucking to. Are they Zeppelin? No, but they make pretty reasonable, popular music, which was this dude's main arguing point - that they're fine if you like popular music. At which point I rightly guessed that he liked Rancid, the Ramones and some other fringe punk band that's very popular with people who don't like popular music, but that for the life of me I can't remember right now. (I was drinking at the time, which helps certain parts of my memory.)
I can trace my firsthand experience with this type of "Popularity sucks!" attitude back to high school, when various factions of friends and acquaintances and not-friends would like and dislike a variety of music for reasons that had little to do with music. The list of the most maligned bands that I can remember probably isn't that surprising - Britney Spears, Eminem, N'Sync.
I also recall joining in without hesitation, but as a result, it meant I covered up my own embarassing musical tastes. For example, it was fine to like Ace of Base because it was ironically cool, but it wasn't cool to admit liking Billy Joel or Alanis Morrisette. The first CD I ever owned was Dookie by Green Day, which is certainly cool and acceptable, but the second was Jagged Little Pill, which isn't, and before Green Day I listened primarily to my relatives' copies of Billy Joel's greatest hits, the Counting Crows and the B-52s.
As I've grown up and matured (I think!), I've come to like my "uncool" musical roots. And, to detest music snobs. It's something I share with Chuck Klosterman, who angrily dismisses people who hate metal in Fargo Rock City. Billy Joel and Alanis are my metal, and as a result, I tend to be more willing to back bands without a lot of critical acclaim than others, I've noticed.
So with all of that as background - Third Eye Blind is fucking great. And I'd rather listen to them than Radiohead or Coldplay any day of the week.