Further to Jim Carroll's post, I would have to make one personal observation. For me it is not technical competence that makes an enjoyable performance, but rather the interpretation of the song. I would rather listen to an out of tune/hesitant rendition by someone who cares deeply about their song and who has taken the trouble to think about it and can inspire me to see even an old favourite from a new angle, than the owner of a beautiful voice picking a song simply because it enables shows them off. In a professional I would hope to see both comptenance AND insight (but still favour the second over the first!) but in the amateur participants of a folk club I would hope I could appreciate whatever people bring to a performance without demanding a certain 'standard'. After all it takes courage and commitment to do ANY floorspot - more so than many people can manage. Just a personal thought.