I really hate being asked this question. I never know what to say, I never know how to being, how to craft any sort of general statement of principles. Usually, I'm just as vague as possible: "Oh, lots of things " and hope that it stops there.
I have trouble defining my tastes. I like things that are difficult. I like things that are hard to find. Things recorded in people's bedrooms. Things created by people who use this as their set of rules to live by. I also like a lot of really silly/dumb/vaguely popular songs that you wouldn't expect that I like. I don't really claim to have widely ranging tastes (had I used the term "eclectic", you would be justified in shooting on sight) or a wealth of musical knowledge I just like what I like. Still, I'm never quite sure how to talk about that with just anyone, you know.
Many of my current friendships started, at least in part, by having at least some musical tastes in common. I never approach someone new with any sort of blanket statement, such as "Hey, I dig that spacerock scene"  or "Hey, that's my favorite type of four-track. Do you like noise?" .
Rather, I just slip subtle hints in when I speak, like carrier pigeons, hoping that one of them will hit their target and an instant bond will be formed. If I was talking about doing my laundry, I could casually mention that I folded socks while listening to Branca's Symphony No. 6: Devil Choirs At TheGates of Heaven  or slip in that I feel Charlambides is an excellent band to make soup to, ride the bus to or just coast away on the couch to. Those are just examples, though. If those don't work, I can always think of more.
Only a small connection needs to be made the rest just rolls on from there.
Next in irritation to the "So, what music do you like?" question (which I realize is just a way of being friendly. It's a standard question, and 99.9999 percent of the population doesn't mind answering it, unlike me, and has answered it, happily and readily, many times) is the "Why don't you bring any of your CDs into work to play?"
Now at this point, I just want to say stop where you are. Let's not go in that direction. Let's go about our duties and forget this moment ever happened.
I do bring my CDs to work. I listen to them in the car, I listen to them in my CD player sometimes, but I never never never listen to them with someone else listening as well. I know better than that.
At home, sure. At parties, sure. On dates, sure. With random strangers, sure. Never at work, though. My the-only-good-defense-is-a-good-offense strategy at work is be Generic Person. I'll talk about things my life, books, music, things in sort of vague terms. Hinting subtly that I have a deep inner life, a pool of thoughts and feelings and things that you could easily know about if I didn't work with you, of course. I'm sure this is completely unnecessary, but it's how I cope with work. I work better if I keep my guard up and I'm just there for the job.
Plus, people never like anything I bring in. I've had bad experiences with this before, back when I was much more evangelistic about what I liked. People act in ways you wouldn't imagine when listening to something they don't like:
"That's not music." 
"This guy is he playing a lawnmower?" 
"Do you really like this shit?" 
"Dude Sesame Street music!" 
You get the idea. I'm not against "sharing" and "learning" per se -- some things I just like to keep to myself.
 Like that would ever come out of my mouth.
 Don't worry, I don't actually have a favorite type of four-track. They're all alike to me. Put the tape in, turn some knobs, something might happen. This is also something I would not actually say, not to anyone, not alone in the shower, not even in a dream.
 A. I wouldn't refer to it by its full name. This is merely a service to you, the reader. B. Not really recommended for folding socks to.