i like to go on after i know everyones started drinking, or at least after ive started drinking, one of those two makes it better.
My motto has always been a show is a show. If nearly everyone there hates it, there will be one person that loves what you are doing. I played at what is basically a sports bar once... It was pretty bad, but there were a few people that were really excited by what I was playing. And because of that I will always accept a show!
every time i play, i play for the beer. people don't stick around for my music, they just want to see if i piss myself on stage or throw up on my equipment. it's worked like a charm so far.
If people don't like what I do I like doing it more, to justify the people that do not like it.