I've said many times, change a song, folk or not, to suit your own needs. In other words, make the song fit you, don't make yourself fit the song. But it does occur to me while reading this thread that there are times when too much change may be inappropriate. I still wouldn't want to censor it, but when you take a song (again, folk, but mostly songs that you know who wrote them) and change it so that it means something entirely different from the author's apparent intention. For a vague example, if you take a song that is about violence, that tells a story about violence being done to particular people by particular others and sing it in such a way that it lets those particular others off the hook, it just wouldn't seem right. Maybe if there is a song which has a theme that is personally repulsive to the singer, if it were me I'd pick a different song. I've often wondered how many "patriotic" spectacles have been held in the last couple of decades by the likes of Pat Buchanan that included the singing of "This Land is Your Land", without anyone knowing that Woody Guthrie was a dedicated communist. I say change away, but maybe don't sanitize a song that was meant to show the dirt.

Humbly, Chet