Llyn Foulkes is a crank. That's a good thing, because we need cranks. We might not want to sit next to one on the subway or listen to one give a floor speech in Congress. But popular culture and institutional art have a way of smoothing out or even debasing life's often painful rawness. Works of art offer contemplative distance, which can make zealous eccentricity especially riveting — illustrated in this retrospective of the painter-musician. Hammer Museum, 10899 Wilshire Blvd., L.A. Through May 19. hammer.ucla.edu.