I'm playing catchup with last week's homework! So the worst performance I have ever seen would have to be Echo and the Bunnymen. It was at a festival back in the early 2000s and this particular festival they had several different musical groups and stages (main stage, locals stage, etc). I always watched the main stage performances. It was time for Echo and the Bunnymen to come out and play and they started to play Lips Like Sugar. Then they stopped. Then they started up again playing the same song. I was under the assumption the crowd didn't know who they were or their music....or maybe they just weren't feeling it, because they walked off stage! Didn't even play the whole song or set! I can't remember any other performances that would qualify as pretty bad, so that is a good sign at least!