In “The Many Faces of R. Crumb,” a comic from 1972, the eponymous underground cartoonist offers readers a crash course in his various personae. There’s Crumb the “long-suffering” artist, bearing the scars of stigmata as he hunches over his drawing table. There’s Crumb the “sentimental slob,” weeping into his booze while treacly music plays, and Crumb the “free spirit,” wandering down the highway with a suitcase and a bindle. There’s Crumb the businessman, the misanthropic crank, and the “