If I want to see a "spot" I'll go to a concert: if I deliberately choose to go to a non-concert event instead, I feel I'm being swindled if I then have a "turn" forced upon me.

I suggest that is how a lot of people think about festival gigs in pubs and applies to both festival attendees and locals.

It is not as if an experienced performer could not turn the customers who just happened to be there into an apprecative audience and that some may welcome the challenge. It is just a little unfair on them and others when this happens.