This thread is the saddest I have ever read. It's so full of people whinging about guests whose crime seems to be wanting to make music and join in.

Let's concentrate on "how to make sessions and singarounds welcome to all, especially the newcomer".

If a regular gets up your nose - try talking to him/her.

I have been a regular at a local session for some time: the delightful thing to me is watching the new performer develop, and perhaps helping. The established and skilful performer shouldn't need any help, and could always put on a concert if silence and attention is so important - then I would expect the audience to be well behaved; in a public bar, let's be tolerant, friendly and enlarge the community of musicians.