A lot has to do with how you are pesonally treated by an artist. I tend to make judgements based on how well I am treated. But I also realize that those judgements have only to do with me and may have no bearing on what that artist has gone through in his/her life which makes them the way they are.
Nick Gerde once said, "If everybody likes you, than maybe you can't be very good."
What I think he meant is that there are personality traits that will be accepted or rejected depending upon where you're coming from. And if everyone likes your music, it means that it has no fiber and is bland and innocuous. It's hard to separate an artist from their personality.
Sinatra was brash, often angry but full of conviction about his art. Elvis found that he couldn't be all things to all people. Hence, drugs etc. Miles Davis was one of the most objectionable human beings ever known but played his horn with integrity, artistry and musicality. I can't say I like his later music but I respect what he did and in the early days played like an angel.
Sidney Bechet is another one. Killed a woman in Paris. Got off. Became a hero. Threatened fellow musicians with a fire arm over stuff like whether they thought he was an authentic New Orleans musician. One of the greatest jazz musicians ever.
Woody Guthrie cut a swath throughout his life alienating many who knew him as well as creating ardent fans.
I don't think that in the folk music field, it's any different than any other area of the arts. Some folks are just plain mean, rude, violent, ugly, self-centered and others are warm, kind, giving, possessing a higher conscienceness and concerned about their audiences. It has nothing to do with any kind of music.