I have just spotted this thread and find it interesting but controversial.

1) Don't you think it a bit narrow minded to suggest that anyone who needs a tiny prompt in case they forget the words should be banned forever more? A lot of people are getting older and find words more and more difficult (however well they know the song) but are still great singers with a lot of experience and a real pleasure to listen to.

2) There's been some talk about musicians 'interfering' in a song session (agreed, not always desirable) but what about music sessions? I've seen singers try to take over what is clearly advertised as a music session. A good session operates much like a singaround with tolerance for all levels of ability, etc. and while the musicians will listen politely to a singer it isn't quite what they've crowded into the pub for.

I think all those points about good manners apply to everyone.