Sorry Jack - people turn up at folk clubs regularly or occasionally, do so to be entertained, and people who run clubs take on the responsibility of ensuring that they get what they pay for.
If a group of people get together and are happy to listen to each other's bad singing they are entitled to do so, as long as they do so in the privacy of their own clubs.
Once they start charging at the door they make a committment to whoever might come in looking for a pleasurable evening.
Jim Carroll