I have very strong views about folk songs, but I keep them to myself. I know that I have a great time when they are being sung, especially when the chorus singing "raises the rafters". Most of the time, however, I listen to people "having a go at singing" and leave it at that. If you become too judgemental, you stop enjoying yourself, and, worse still, make others uncomfortable and self conscious. I actually have more of a problem with musicians, rather than singers, but I still keep it to myself!