A lot of you have probably experienced something very similar, but i'll tell this anyway.
Way back when HMV had a designated jazz section (before it became amalgamated with Johnny Cash, Judy Garland and Muddy Waters - ie. everything outside of pop/rock), I was in the Leeds branch, leafing through the Blue Notes and Prestige etc. when two young lads walked through. They were maybe 13 and evidently in the wrong part of the store.
They looked at me, then at the CDs in my hand, and one just simply said, "Jazz. w***er's music".
I really did laugh out loud.