I personally think that Folk Club manners should really be called Folk Club aims & rules.

Each venue decides what they expect from an evening and should make that very clear at the start of the evening and certainly to newcomers. Better still, if you have a website, put it on there also (that way people who are coming along for the first time, know what to expect). Put posters up on the walls of the venue stating the rules & aims.

We state what our requirements are on our website and on the front of the diary which is handed out at each event. The MC also mentions it at the start of the evening.

Above all enforce it.

I had a young couple come along one night, who as the night wore on, started to get louder and louder, to the point where they were distracting people in the room. I walked quitely over to them and explained the situation. They decided in a nice way, that they didn't like having to be quite, so they discretely left, shook hands with me and have never been back. That's life. It would have been nice if they had come back, but I would rather have the 98% of the audience happy, than bowing down to the minority.