I think that musicians deserve additional compensation when playing gigs where one of the following applies:
1) Obnoxious caterer (I'm opening the floor on this one. Call it "Blog Your Caterer.")
2) Difficult load-in (i.e. basement gig in a venue with no elevator, or in one where the only elevator is really a dumbwaiter into the kitchen which requires navigating around garbage to enter/exit.)
3) Venues where the band has to move the PA/backline setup more than twice (i.e. different setups for cocktails, smorg, chupa, dinner, and desert.)
4) Gigs where the band doesn't get fed.