I had a French teacher who loved Black Sabbath. He owned a vinyl of theirs from the 70's and admitted he constantly listened to them. He was well over 50 also, so it was so unpredictable.
Why is that? My parents are in their 50's and still listen to music from their younger days. I could understand if it was a group like Aborted or something, or like the Heavy Metal Grandparents in NoLordy's signature.
He didn't look it as he was always dressed so formally. My parents never listen to anything interesting (just the Beatles), most older people I know don't.