There's a lot of excellent stuff which I'd like to respond to but a couple of lines caught my attention -

Make sure the guest list reflects the considered views of the audience...not the personal likes and dislikes of the organiser(s).
Waddon Pete

It really doesn't matter what you put on Paul. You organise it and it is your call.
The Villan

We should never forget that, for the most part, folk club organisers are volunteers doing a lot of hard work for the love of it. What's more, they are part of the audience.
Of course they should take suggestions from the audience but having to put on guests you don't like to put bums on seats is likely to make you wonder why you're doing it.

I'm with The Villan on this one.