I guess I get to tell my "semi" walk out/got up and quit story...
I was filling in with my singer's acoustic show on a Wednesday night(he and I do our own show on another night). The show goes from 9p-1a. At some point during the night, some "touring act" none of us had ever heard of, came in and started drinking. At first, they seemed pretty cool, but as they drank more, they started to get a bit obnoxious. My singer starts inviting them up to do songs with us. Most of the time, that is a horrible idea and it's usually a mess, but we figured since these guys were "pros", it couldn't be that bad. We were wrong. Since they showed up around midnight, We had an hour of trainwreck after trainwreck. I get not knowing a song, but if a band asks me to sit in and play a song, and I don't know that song, I'm not gonna play, or I'm gonna suggest something that we all might know. Not these "rockstars". Whatever song was mentioned, whichever of these fools was playing whatever instrument they were on just said "count it off" and proceeded to demonstrate that they clearly had no idea how that particular song went...
About 1:30a, the drummer for this band was falling of the drum throne when "Hey Man, Nice Shot" was suggested. I'm already irritated. I don't mind playing over, but these jackwagons had made the night no fun, and I was just filling in. So my singer announces this is the last song and I start into the riff, which I've played a zillion times, this moron behind the kit yells "Dude, you're playing it too fast. Slow it the @#&* down." . I turned around, smiled at him and said, "then you better go wake your bass player up and get his ass up here, because this is how the song goes, and that's how I play it.". I put my bass down and walked off the stage. Technically, the show was over when I bailed, but that was the one time I walked off stage and didn't come back...
Don't wanna be too judgmental, op, but I played without a monitor for almost 2 years, and I've played gigs worse than what you dealt with. Unless someone is trying to light me or my gear on fire, if I'm getting paid, I will soldier on to the bitter end. I am sure as hell not leaving any of my gear behind...