Surely if you go out for an evening and shell out the cost of a pint to join in a social gathering of fellow amatuer enthusiasts, that's one thing. Same as going to the local Am Dram Society or Writing Group?

And if you spend a tenner to go and watch a professional act perform, that's another.

So long as the organisers make it fully clear to punters what to expect, then can't everyone enjoy what it is they choose to?