You're right, of course...if the audience paid good money, they should at 
least get a competent show, and my sympathy for the musician in question goes 
down in reverse proportion to what they're making.  Although I must point out 
there are times when the musician is barely getting paid...certainly on the 
indie- and mid- level and with Clear Channel forcing large unpaid promotional 
concerts for their radio stations, sometimes for the bigs as well.

<< > like what Stewart said about what a musician "owes" the audience, 
because it's
> not as if the audience owes the musician anything.

Actually, I disagree. As Ryan just pointed out, what the audience owes the
musician is money. And an audience at a rock show has generally ponied up
and held up their end of the bargain. Sure, there are tired performers and
apathetic audiences, but if they're an apathetic audience that's paid
money for admission to the performance, the onus is on the artist to,
well, perform. >>