What you listen to can have a huge impact on your life. When I was in a stage of rebellion of my life when I was about 12, all I listened to was hardcore rock music and the sort..... just terrible music..... full of swearing, references, etc. And I found that after listening to that for just awhile (for about 2 weeks) I was saying the same stuff that I was listening to. Yes, I was swayed easy, mainly because I was in a state of rebellion, BUT, the music still had an impact. If I hadn't of heard some of the stuff in the music, I wouldn't have even said it in the first place.
All I can say is this: just listen to what you're listening to! (I hope that makes sense.) Think about what is being said. If it's bad, try not to dwell on it. For me, I just can't stand listening to swearing and references in music, it makes me sick. It's kindof being hypocritical, you know? Colossians 3:8 deals with filthy language. If filthy language is condemned, then I can't even begin to bear listening to it.
There are actually a lot of "good" secular bands out there, actually, but that doesn't mean what they're singing is "good." I mean, Blink182 is awesome, and most of what they sing doesn't express something immoral and stuff like that... but there's the occasional "immoral thing" in their music. I wouldn't stop listening to their music though.