My worst was Guns n Roses at the old Texas Stadium in Dallas. They were playing on what was one of the most bizarre bills of all time -- The Smithereens, Ziggy Marley, Iggy Pop, GnR, and INXS. Made no sense and you could tell GnR was absolutely not interested in being there. I think they had to fulfill some contract obligation or something -- their tour was done and this was the add on show that came between them and taking a break. It started raining at the beginning of their set and they were all pissed, but Axl being the lead douchebag finished it up a few songs in by saying "Everything's bigger in Texas, so I guess you guys are the biggest faggots too," flipped us off, and then walked off the stage. What a chode. Wild how the crowd can love Iggy Pop for giving us the bird and then hate Axl so much for doing the same thing. A study in a crowd's ability to recognize a genuine badass from an entitled dipshit.
Apparently GnR concurs that it was their worst show ever: https://www.a-4-d.com/t1373-1988-09-17-texas-stadium-irving-usa