A poet who comes to a local club never practices a reading because it removes the spontaneity (so he says).
He misreads words, cannot scan correctly & cannot perform even a limerick without a book.
He asked my partner how many songs I know from memory.
She said she didnt know but it was at least 200.
He said,'Is that all, I have about four hundred'.

I did feel I was wasting my time learning the words & practising guitar before performing if I could satisfy the audience just reading from a songbook.
Individuals have their own personal standards & its up to the organiser to decide if the audiences tolerance level matches the performers.

To get back on thread - manners in folk clubs should be based on 'Do unto others ....'
If I was at a rock concert I still would try not to disturb others with my activities.
Manners really!