That's just the 'prickly' attitude that deters some people from joining in... I've unwittingly been at the wrong end of it a couple of times, and I make damn sure I'm not guilty of it when I run a session, or a Singers Night at the folk club.

Agreed there have to be rules of etiquette, but there's a right way and a wrong way to apply them. Making people feel uncomfortable is the wrong way - from both sides.

Politeness and courtesy, please...

Even when someone barges in and makes a nuisance of themselves, give them the benefit of the doubt and gently show them the way your session runs. Yes, there will be times when it doesn't work out, but remember not to destroy the very atmosphere you are trying to maintain...