"sometimes it's "never heard of him/her/them so I won't bother going", which could be a bit of a blinkered view"

I think folk clubs should never rest on their laurels: remember to educate your regulars about someone who might be new to them. Put up posters with an eye-catching image of said performer well in advance (with a clear website URL on it). Hand out fliers explaining who he/she is.

I guess it helps to have a regularly updated website that you're confident your regulars look at.