I saw Guns & Roses at Storyville Jazz Hall in New Orleans just as Appetite was beginning to break. They were so fucked up they could barely play at all, and Axl sounded like Janice Joplin on crack. Worst live band ever.
Worst gig I've played would go hands down to the time we were supposed to have been booked to play a party for what was described as a "bunch of rowdy navy guys", after we had explained that we were a loud, hard rock band, to which the guy who booked us replied "no problem, you'll be perfect!".
When we got there, and started wheeling in the half stacks and large pa columns, imagine our surprise when we encountered a roomful of 60+ somethings, replete with wheelchairs and oxygen tanks! One guy actually asked us if we knew any Glenn Miller!
We set up amongst the glares of the geezers, made sure we got our money in advance, and by the third song, the room was completely empty except for us and the bartender chick, who was at least into it! We actually played (most of) a second set for the younger guys who were outside during the first set cooking on the grills, and they were having a great time (all 15 of them!) until a huge, fat bastard waddled out from the door on my side of the room, started screaming and spitting at the top of his lungs at us to turn down (in the middle of a song), that he was the manager of the building and was shutting us down, and the fucker actually acted like he was going to reach down and pull the plug to my power conditioner out of the wall, at which point I put my guitar down and chased him back through the door he waddled out of, telling him I was going to stomp his guts out if he even thought about touching my shit, to which he replied that he was calling the police and disappeared! Needless to say, the show was over, we played 1 & 3/4 sets and still got paid $700 for it!