Sleepy Rosie,
Does your analogy about the watercolor club include putting on an art show in a public place? Do you think that really bad art should be displayed?

There are a few different venues being discussed in this thread: private singarounds or sessions, singarounds or sessions in public, paid gigs. I think they each have their own requirements for competency. I'm glad that no one here seems to think that anyone of any ability should accept paid gigs.

I don't think that folks who can't get through a song should be out in public trying to do so. On the other hand, I would never dream of trying to police the situation. I would just form my opinions of the performer and the venue and move on. So the number of people who have been accosted by the competency police doesn't really reflect the opinions of the listeners. I think perhaps I'm feeling a bit like I spent years getting good enough to perform, and others should do the same. Totally self-centered, I know.

If you're not in public, anything goes, as far as I'm concerned. Experience playing or singing for others is almost as important as practicing.

I also strongly believe in encouraging beginners, finding positive (but true) things to say to them, and helping them in any way I can. I also try to find kind and supportive ways to let them know where they should concentrate their practice efforts.