Without mentioning names, I've heard many folk musicians who make listening to folk music just slightly more bearable than going to the dentist. I've also heard too many folk musicians... especially some bands where the musicians seem so intent on cracking themselves up that they ignore the audience. It's as if the audience is being "allowed" to listen in on a private jam session. Too much background on songs, right down to record labels is generally boring, too. But most of all, folk musicians should at least look like they're having a good time singing the music. After all, people are paying to hear you sing, and they come to have a good time. I think your brother Warren is right. Somewhere in the middle is best, though.
Jerry