Hmm. I'd imagine you'd end up blocking a lot of good songs that simply have the word "fuck" in them, in a non-aggressive, non-sexual way, and may still have to endure lyrics that sound like a 13 year old bragging about how cool he is (yeah, that's mostly rap but not exclusively)

This is a bit of a wide net I'm afraid. That said, someone else pointed out that I might be able to hide artists. That could be a partial surrogate for blocking a theme / specific content.