Y'know, it really depends on the music. If it's something that tells a story or has a point to make (Pink Floyd, Rage Against the Machine, SoaD, etc.) then I pay attention. But if it's just a rock singer singing about chicks, cars, drugs, how proficient he is with his cock, or how much his band rocks, then no I listen to the music. I've been singing along with AC/DC for 30 years and I don't even know half the words. I just make sounds similar to what I hear (hey not my fault Brian Johnson was totally unable to be understood in an era when you couldn't look up the lyrics online).