I have been interested in Folk Music for 40 years now. In all that time I have only known two people who have actually been banned from folk clubs (as opposed to not receiving an enthusiastic reception - which, I suspect, many people on this and similar threads interpret as being 'banned'). One of these two people was banned because (a) he was disruptive and (b) a really bad singer. The other person was banned because he was a really, really, really bad singer. Interestingly, they both chose to sing very, very long songs (no, not traditional ballads) and their floor spots therefore seemed interminable - there's a lesson there for us all!