The important thing to realize is that listening to a certain type of music won't condemn you, nor will NOT listening to certain types of music save you. Christianity isn't about a list of rules, it's about a relationship. It's about admitting that we can't do it on our own and seeking an intimate relationship with Jesus. Many Christians feel that certain music gets in the way of their relationship with God, so they try not to listen to it. Other Christians feel that God has asked them to give up listening to certain music and it's necessary for them to obey (disobedience will ruin the relationship).
But, some Christians never feel like music gets in the way, some aren't convicted of it yet but eventually as they mature in their relationship God will convict them of it. Some Christians aren't really in a deep relationship and aren't actively pursuing it and are what Jesus called "lukewarm". They don't feel music makes any difference, which it doesn't because they aren't close enough to Jesus to tell.
For me, I'm careful of what I listen to, but I can listen to secular music usually for a while without it bothering me (I don't pick up on lyrics anyway, it's strictly a right-brained experience for me) but eventually it will start affecting me and I'll turn it off or switch it to a Christian station. Certain music, though, I can't ever listen to because it weighs heavily on me.