I don't mind watching someone who is a bit drunk performing, so long as it doesn't ruin the music too much. But where I personally draw the line is at paying to watch a self-destructive drunk perform. That makes me feel like I am encouraging them to ruin their life. I remember watching Johnny Thunders (ex-New York Dolls I think) many years ago - and when he started dribbling vomit as he sang I just felt guilty at colluding at his state. Really sad.
I've drunk an enormous amount over the years - and am still at the stage of regularly giving up (getting more & more sucessful at it now - esp since I've developed some nasty side effects when I do drink). I generally enjoy myself much better when I'm not drinking now. So whilst I wouldn't presume to tell anyone else not to drink - I would like to make the point that abstinence can make you a happier, healthier more confident person & can improve performance. Its always worth a try....
I think a lot depends on what kind of drinker you are - some people can manage moderation, some can't. Unfortunately I usually can't - so drinking & attempting to perform are a mistake for me & I expect that I'd become increasingly painful to watch/listen to.
Looking back at the original post it seems part of the problem was that they weren't 'with' the audience - perhaps they were using the drinking to seperate themselves from the audience (ie like a little club of their own)? - drinking can sometimes be used almost aggressively to reinforce a 'them & us' division.

Kris