Advice from stand-up legend George Carlin from an interview on Comical Radio, a NYC weekly radio show of interviews with comedians:
If you die on Saturday night with your stuff, but it worked great on Friday and it worked great on Thursday and it worked great last weekend, it's not you, it's not the stuff, it's them. And once they're resistant if you do happen to get the luck of the draw with an audience that is not just right, sometimes you react to that subconsciously and you feed off it and you don't do your best. But it's not the material, it's just the performance that night, because the performance happens between you and them, so they share equal responsibility. I mean, that's the way I've always looked at it. I used to die on a Saturday night down at Greenwich Village at Cafe au Go Go and I'd say "well what's wrong?" and I'd remember the night before and I'd say, man, everything worked great. And I would just let the two cancel out and forget it and go on and do a set on Sunday night.
This goes against the "it's never the crowd's fault" theory. And it seems to be the mindset that Carlin needed to transform himself from, as he puts it, "Suit and Tie, Nice Guy, People Pleasing Time" to the more volatile and real act that he does today.