It seems fairly obvious to me - guests are generally paid and therefore are expected to be professional or semi-professional and held to a higher standard than amateurs.

Singarounds give ordinary folk the opportunity to sing out the songs they love, mostly to the best of their ability. Granted there are some who don't sing very well or who tend to rely on crib sheets and there are a very few who make no effort to improve or to try a song with a piece of paper in front of them, but the idea is to get together and share a love of traditional music. The majority of venues I have been to everyone listens to whoever is performing, whatever level they are at.

I have been in the position of sitting next to someone who just wants to chat through other people's performances, but I think there are some people who just like the sound of their own voices and there is very little anyone can do about that, other than ignore them and make it clear that you are there for the music, not to talk.

I would also confess that I have been at venues where one or two performers were not my cup of tea - maybe doing non folk stuff at what is purportedly a folk session and not even doing that well. I will quite often use there turn as a good time to go to the loo, or to get another drink, so that I don't miss the people I really want to hear.