Yeah, it's just with me, I prefer to understand what one is saying during metal, cuz they're a buncha mean dudes. Like, for example, he could be saying this while screaming: "I'm gonna slaughter your family and eat your soul and make sure I bury you alive somewhere off the coast of Asia!" And I'd be all like: "DAMN THAZ AWSUM!"
So yeah.
Of course, it's a whole different case for some reason or another when listening to foreign music, but that's a whole different topic.