Well, and please remember this is just my two cents, okay?
I loved Alice Cooper, Ramones, Motley Crue, etc.... I turned out to be a well adjusted individual with a hard working mentality, good morals, and good family values.
What I'm getting at here is that it's more the parenting than what music your kids are listening to that counts.
For example, I let my teen son go to a Marilyn Manson concert. Why? 1) He knows our values and 2)He is aware that most musicians only do wild antics for the attention. Also, Manson is not preaching religion at his concerts he's putting on a stage show. I waited in line with my son (the other people in line were actually quite nice) and my husband went to the concert with him, not because he likes the music, but because we want to know he is safe. My husband's take on the concert? "Typical rock concert."
Personally, I don't mind the concerts. My child knows our values, he believes in God, and is growing up to be a respectful person because of our parenting.
Our parenting principles are pretty simple: Respect people, help people when you can, take responsibility for your actions (I do not tolerate excuses), do not lie, and remember that you're a member of this family and, as such, we look after each other and we all contribute to work around the house.
DJ