A man who is on the run or otherwise trying not to be recognized will often grow a beard as part of his attempt at concealment. The inversion -- where a heavily bearded character shaves for similar reasons -- is also relatively common, doubling as an Important Haircut. A sufficiently Crazy Prepared character might grow a beard so that, sometime in the future, he'll be able to shave it off and go unrecognized - maybe this is the reason for the Beard of Evil? If the character in hiding is ashamed of what he's done, it may also count as a Beard of Sorrow.