This thread seems to have drifted from manners to who should or shouldn't be asked to perform...

I've very rarely encountered bad manners in a folk club. In one instance a guest appeared only for his own slot and spent the rest of the time outside, but he was essentially a pub entertainer rather than a folkie, so that may be down to culture rather than intentional rudeness. The same may be true of those who chat too much while others are singing, but I do agree with an earlier post which suggested that it's the responsibility of the singer to dominate the room, although that's easier to do with a loud voice or a big squeeze box.

As regards who should or shouldn't be called on to sing, it's good to have singaround nights where everyone gets an equal chance, but on guest nights a good MC will exercise some discretion after, ideally, giving everyone at least one opportunity to sing.