People who get on my case for being "close-minded" by not listening to many different styles of music. Alternatively, people who claim to like "every kind" of music. They're both full of shit.
For the first one: I mostly have metal, rock, and punk on my computer because that's what I prefer to listen to. Since I've had to find most of the music I enjoy on my own, that is, without anyone else's influence or suggestion, until college (3yrs ago), a lot of that music happens to be less than 20yrs old. Usually, this means taking a lot of crap for not listening to Zeppelin, The Beatles, Sabbath, Hendrix, or any of the other huge musicians from the 80s back. Combine this with the fact that I'm just not a fan of classic rock and can't stand jazz, and damn near every person I talk to invariably says I haven't tried "Band X" enough if I don't like listening to them, especially in regards to the "classics". Not everyone is going to live like the 80s is the best thing that ever happened to music, and just because a ton of bands claim Zeppelin as an influence doesn't mean I'm necessarily going to like them if I've heard those bands first. What was innovative then is not innovative now, so working backwards as I've had to tends to skew things in that regard. If that analogy doesn't work, take any 13yr old and give him a 56k modem, and see what he thinks about dial-up; the internet today wouldn't exist without it, but that doesn't mean it's something that needs to be revered by everyone.
As to the second point, those are usually the people who are worst about rant #1. And I say this mostly because "everything" tends to mean "rock, indie, jazz, and metal up until Metallica's Black Album because screaming scares me". Guess what, princess, you take a style of music founded on the blues, then covered in a nice coat of anti-establishment thinking, and it will invariably find ways to offend your radio friendly ears. Stop pretending like you like all kinds of music and just admit that you're only saying that to pretend like you're open minded. I can listen to just about any kind of music if it's playing at a restaurant, or I'm watching a live performance, but that doesn't mean that I want my personal playlist to go from death metal to reggae when I hit shuffle.
/rant