Absolutely the B-52's in about 1979. They turned up the stage & house lights between each song to reprogram the primitive synth/keyboards & played totally out of synch. The drummer was dodging thrown paper drink cups of ice all night (none thrown by me).
Another bad one is/was a guy who played a couple of gigs a while back at the Irish Pub where I work a night or two a week. He may have done 1/2 of the Irish Rover, if that- no other folk/trad songs that normally go over really well. Poor execution, limited repetoire of bad rock/pop songs that he mercifully abandoned after 8 bars or so. Stale jokes (in bad taste) and innumerable requests for tips/free drinks.