In my experience of folk clubs and sing-arounds, there is no such thing as a set list. Floor singers just sing whatever they feel like, traditional or not, and musicians often play tunes whose names they do not know. If there is a guest, he may well have a planned set, but often includes many requests.

Nor is it possible in many cases to identify the audience. Quite often, the performers have only a corner of a room, so going round asking for a contribution may not be possible.

It does seem to me that many people are under a mistaken impression of how folk events work or even occur. As a member of a Morris side, we often used to descend on a pub more-or-less at random at the end of a tour and ask if we could play and sing in a corner. No organisation at all.