There have been a few performances that I probably should have walked out of but didn't.
For example, there was a play at Sheffield's Crucible theatre, dealing with complex lesbian issues that I couldn't really make head nor tail of. One of the lead performers seemed to spend quite a lot of the time, totally naked, 'pleasuring herself' with a rolled up magazine. (I wasn't particularly offended; I just couldn't understand wy she was doing it!).
Several people left during the first act, with at least two thirds of the audience not returning after the interval. By the end of the play there were just a a tiny handful of people left (including me), all of whom appeared to be equally baffled by the whole thing.
I can't remember whether or not I walked out of Roger de Courcey's act at Butlin's Southcoast World in Bognor Regis but I know that I definitely should have done. He was totally pished and spent the whole of his 'act' doing nothing more than ranting aggressively about people at the BBC who he thought had ruined his career, with not the slightrst hint of humour.
Another time that I really ought to have left a theatre, but didn't, was a performance by a professional orchestra in Adalaide. I've heard better school orchestras!
Lastly, it was only good manners that kept me (and several hundred more people) in our seats during a coference plenary session, also in Adelaide. We'd all failed to notice that the two-hour lecture, which we sat through and politely applauded at the end, was going to be given in Japanese!