as one of the most insistent 'trad' defenders, I find I kinda like the definitions offered by " llareggyb "

" anything goes for us so long as it has entered the general cultural consciousness, at least that of the "folkie" community (definiton of folkie: people like us)

This is the basic attitude I 'put up with', as long as newish, songwriter, commercial stuff doesn't become the majority. This IS how various music becomes folk/trad, so it needs to be recognized. Unfortunately, for some of us...(like me)... the process goes much too fast these days, and people want to include everything THEY liked or were familar with as kids...so the Beatles and Dylan are being offered status in just one generation.

Anyway, if an evening includes ONLY a few such things that have recently"entered the general cultural conciousness", I'll survive.
(unless the evening/event has been specifically planned as a trad/folk event!)