well I live in Ireland ,I visit folk clubs in England more often than Jim Carroll,so Iam fairly well qualified to pontificate.
firstly sessions in Ireland can vary as they do every where,recently at a session, a persistent pain in the arse who tried to howl or sing during a set of tunes had to be told to desist.,the same had to be said to A Djembe drum basher,who had his own rhythym.
secondly rudeness at folk events is nothing new,but to put it in perspective is fairly rare,with respect to every other contributor,I have played many[thousands of folk events] over the last thirty five years,and the worst rudeness occurred to me at Crewe and Nantwich folk festival in 1985,the mc were Garside and Gough[ now smooth ops]they allowed three drunken yobs,to get up and harass my ex wife Sue Miles,asking for stranger on the shore,and wanting to play her clarinet,.and were completely ineffectual as mcs.
that was 24 years ago,and to be honest is the only rudeness that I can remember,so must represent about oo5 per cent,there may have been one otr two others but I cant remember them now..
try playing working mens clubs ,then you get the treatment,most folk clubs are very polite,some here have argued that they are too polite allowing sub standard performers to sing.