"My guess is they come because a folk club is one of few places they can get to play their music to an appreciative & warm hearted audience, which is generally what you find in a folk club and why the music - any music - tends to be accepted as such."

Unfortunately, there's a lot of truth in that! It's what I've been saying for ages! Far too many people have taken advantage of the easily accessible platform provided by folk clubs. My view is that if such people can't get platforms anywhere else it's their problem, and they should not be making it a problem for folk fans like me!