To catch up with Lizzie's post of some distance back, I speculate that the reason Americans don't appear to have this problem is perhaps that they have a culture which implicitly discourages people from trying to perform until they have mastered the basics. This was certainly the culture in the UK when I started doing floor spots, and I would have been embarrassed to have got up without being properly prepared (that's not to say I didn't make plenty of mistakes!).

How do you deal with persistently poor singers? It's got to be a judgement for the organiser, it will depend on the club, and on the singer. Some poor singers are nevertheless viewed with affection by other club members, whereas others are just an ordeal to listen to. The organiser has to be sensitive to his audience, and decide whether to tolerate the poor performer, or give them only occasional spots on evenings where it won't give a poor impression of the club (ie not on major guest nights). If poor standards of performance seem to be discouraging audiences then the organiser may have to say, sorry, you're not good enough. It may not be easy to tell someone that, but that's something they'll both have to come to terms with.

No one has a right to sing, not even at a folk club. The discretion must always lie with the organiser - they're the one taking the financial risk. They decide the club policy - even if the policy is that there is no policy!