Art, Bill D, Mary, Steve and others - I too think I know the person you're referring to, and he shows at my performances as well.

Some of the folk-club organizers get mad at him because he can be a bit disruptive at times, but all in all, he's a harmless divil. Very knowledgeable about the music and musicians, which he will discuss loudly, in depth at less than the drop of a hat.

It's my belief that he has Asperger's syndrome.
He's less a pain in the ass than most drunks.

Seamus