I've been thinking about the story where Keith Richards sees Chuck Berry's guitar in the case, wants to play it, takes it out, and then Chuck sees him and decks him a good one. So here's the question: would you have done the same? I suppose the corollary is whether it was morally permissible. My take: what Chuck did was entirely reasonable. Keef was being a jerk. You don't just pick up another person's instrument without permission. If you do, you should be prepared to accept the consequences. You never know how sensitive they might be about that stuff. My general policy, in fact, is not only don't I touch somebody else's instrument without permission, I don't even ask to do so. Ever. Asking puts them in a potentially awkward spot where they have to say no and look impolite doing it. I've been in that awkward spot on the other end, and it's no fun.