Hear To Learn: Could it just be that you are not wired to detect sarcasm as such? I know a couple of folks like that and they take everything I say at face value -- which with me is NOT a good idea!
Personally I think your original premise and title is not flying too well in this thread. Maybe just setting it aside and not feel the need to defend every word and refute every misunderstanding may be the best course of action here.
Or another option would be for the community to not support/encourage those making fun of the music the guy was asking about?

We can make the community a more friendly supportive place or we can blame the person who is offended for not being tough enough or understanding we were just kidding. I prefer the former!