When Michael Jackson died in June 2009, each person who knew enough about his music and his life to have an opinion on either (that is to say, pretty much everyone all over the world) was forced to decide: Did his personal behavior detract from the value of the music he made? Did the increasingly bizarre plastic surgery make the pulsing beat of “Billie Jean” less danceable? Did the allegations of child abuse make “Man in the Mirror” less true? More than a year later, there is no clear consensus, and likely there never will be. Since the first caveman painted on a wall 32,000 years ago, we have sought and failed to separate our perception of art from our perception of those who create it. “I guess that’s a pretty good picture of a bison hunt,” some Paleolithic wag surely said, “but coming from Ogg, I’m just not sure. Isn’t he a vegetarian? What does he know about hunting?”