A lot of sense from posters here. If you want others to listen you have to be worth listening to.

At a folk concert or in a folk club an audience of singers is invaluable. To hear a good chorus well sung is a treat. I recall the old days at Folk Union One at the Bluebell, Hull when guest singers would be startled by how quickly the audience could pick up a chorus and add harmonies to it.

As for pub singarounds of course they are going to vary as to who's there. Some singers will listen and join in choruses and some won't. And some non-singers will listen and some will just have loud conversations that become louder if the singer increases volume.