Here's a link to a page about "R. Crumb and his Cheap Suit Serenaders" - "a loosely organized string band playing songs from the 1920s and (occasionally) modern songs styled after the songs of the 20s. They recorded three albums in the 70s and occasionally are active today, though usually without Mr. Crumb who lives in France."

With a link which gets you sound samples. Very wholesome stuff. I get the impression that once the vitriol was out of his system he'd play sweetly on the mandolin.