I don't recognise some of the sessions mentioned above - I've played my guitar at a fair few and never felt any antipathy. I make a point of not playing if I don't know the chord-run of a particular piece, and if there's an obvious 'guitar-leader' I stick to whatever chords he's playing (even if I know a run that sounds 'better' to my ears).

And at the sessions I've been to, I've abstained from singing unless aked to do a song - and that seems to happen at most of them.

Maybe we're an especially friendly and charitable lot around the Lincs/Yorks/Notts border region?