Music is beyond the lyrics, the tune, the harmony etc. music is all about the spirit behind it, the motivation behind it. As we all know, there are only two main spirits in the universe bad, which is the devil's, and good which is God's.
You only have the good spirit, when you allow Christ to take over your life, i.e. you are born again, or else you have the other spirit, which is the devil's.
What am trying to say is, look at the artist's life, if they is born again, listen to their music, if not throw it out. if you cant tell whether or not they are born again (i.e. they are lukewarm) throw it out.