Midway through Keith Richards’s largely genial Life, he uncorks a sudden barrage of invective against the film director Donald Cammell: “He was the most destructive little turd I’ve ever met. Also a Svengali, utterly predatory, a very successful manipulator of women. . . . Putting people down was almost an addiction for him.” Only the narcs and his frenemy Mick Jagger (mocked for his now infamous “tiny todger”) come in for comparable slagging off. Why Richards should harbor such animus