Some songs though, do go against Islamic ideals, and I definitely think it's best to stay away from them. Songs about hooking up and boozing it up especially. Songs about love... well... they are borderline. As a married woman, I see no reason not to listen to them. They might talk about making love and they might be sexy, but I have my husband to turn towards and feel that way about. It doesn't cause me to lust or feel anything unislamic. These songs might be best not listened to by the non-married.
I feel that it depends on mostly two things:
1) What the content is. Is it against Islam in an obvious way like speaking of adultery, pre-marital sex, partying, etc.
2) How it affects the person. Does it make you, the individual listening to it, feel or do unislamic things? Does it have a negative effect on your life, however small?
If a song speaks of unislamic ideas in a way that makes them seem OK, this is not a song that should be listened to. If the music talks about, for example, love, not mentionning that it is between an unmarried couple or anything, it could be OK, but if it makes the person listening to it lusty, then it is not OK for that person. It has a negative effect on them. If music is your primary love in life, then it's not OK for you because it's making you lose sight of priorities.
Done in moderation, I feel music is just a blessing to life.
Islam always seems to clear about things. It's yes or it's no. Or it's sometimes, but in very specific conditions. I think that music is not so easy to put a ruling on. I feel it varies widely from person to person and can depend on their individual situation.