At the recent Isle of Mann coverage, the topic of conversation was grandmaster superstitions, during which GM Simon Williams conveyed that Karpov would only wash his hair when he lost a game. Apparently he went over 40 games without a loss during a streak, leaving it up to our imagination on the consequences.
Now I know GM Simon Williams is quite the joker, so I'm inclined to believe that this is just one of his jibes, but is there perhaps any truth to this? I found some references to this with Google, but I'm not sure about how authoritative they are.