We've had a couple of people who've tried to throw their weight around at our chorus. Because I tend to speak before I think I have managed to surprise them and shut them down, and both left in the end. We are otherwise all very friendly. I sometimes wish there could be a bit more said about, say, people who don't learn their part, but on balance I'd rather we stuck with our all in it together ethos and work on the bad bits without getting personal. That's what quartets are for, to have a good moan about the chorus and get it out of your system!
I find it embarrassing when I go to church choir (after they've begged me to come because I'm a big slacker) and they go on about how good I am. I'm not, but I can sight sing which they mostly can't. Far from feeling threatened they are embarrassing in their self depracation, and I always make a big point of saying how well a particular part sang, or whatever. They are just the nicest bunch of people you could ask for. They did have one mad lady who took offence at everything and thought everything said about 'the sopranos' was directed only at her! She left in a huff one day and nver came back.