Problem is, in that type of situation, although you may get agreement that the boor is being a boor, most of those who agree aint going to put their heads above the parapet. It comes down to 'anything for a quiet life' and, if they know that there will be any sort of reaction from the guitly party then they will not take any action to stop the abuse.

I was in this position a few years back with ignorant performers not only not doing folk in a folk session but then talking through the performances of those who were doing folk songs. The general position was 'live and let live' which really pissed me off. I took to visiting the loo or ordering drinks when one of them was doing the latest interminable Oasis song (badly) or another was singing 'Summertime' for about the tenth week running.

In the end, and as it appeared that the people running the session were not prepared to do anything about it, I stopped going. Soon after that the sessions fell apart and a group of us started up a new session on a strict 'folk' basis.

These idiots, like some posters to this site, have no interest in other people. All they want to do is give their own inflated egos an airing, usually at the expense of others. All they really do is make themselves look small and petty and ridiculous.