The Joshua Bell as subway musician story has made its way around most of the musical blogs already, but I'll join the fun and link to it as a service to those readers who don't always frequent other sites (like, say, my mom).
Personal analogue: my college roommate Mark used to have a gig playing lounge piano in the lobby of a fancy-schmancy apartment building in Chicago, and I would sub for him every now and again. How little attention was being paid? I could leaven my directionless Dukelsky-esque noodlings with entire pieces by Schoenberg and Feldman with nary a raised eyebrow from the residents. Ignoration has its perks.
(Actually, there was one guy living there who did pay attention. Whenever Michael Morgan walked through the lobby, Mark would segue into the most incongruous bit of operatic repertoire he could think of. There's a certain unique fun in pitching your act to the farthest corner of the room.)