If "too many of the people who get up to sing are of that standard", perhaps it is the standard--and you are in the wrong place.

Audiences for floorspots, or open stage/open mike, or whatever you call them, should expect a very mixed bag from those who chose to perform for them.   If you got what you paid them for, you'd get exactly nothing--so if you're entertained by anything at all, you're ahead in the game.

The idea that all those other performers are "boring and embarrassing" can be rather self-serving--If I thought a performer was"slumming" just to show up singers and musicians who weren't as talented or experience, well, that would bore and embarrass me--

And it would really be embarrassing if they really weren't any better than the performers they were so smug about--Well, it wouldn't really be embarrassing, it'd be funny--