Seeing as how I don't drink or do drugs, I can't really say.
I do dislike it when people I rely on to do their job are underperforming / not performing at all due to drunkenness, though.
The classic example would be people dicking around in WoW raids, though I've also been subjected to the same in numerous shooters.
It's not always that bad, like if you're just having a bit of fun playing Modern Warfare 2. Especially if you're in Free For All.
But when you're trying to teamwork in SWAT4 and some idiot keeps shooting the hostages 'cus he's too drunk to tell the difference between a guy in a white lab coat and a big, burly man wielding an AK47, with a set of kevlar and a tactical vest... then I get annoyed.
I've even had a guy I play Arma 2 with crash a blackhawk, killing two four-man fireteams, a squad leader and a medic, his copilot, crew chief and himself, because he was drunk at the stick. Basicly, 20% of the people participating in the game had to sit and wait for an hour and a half, because he showed up to the game drunk, and didn't inform people that he shouldn't be put in a sensitive position that day.
Needless to say, a fair few of us let him hear for that.