The only lurking bassist I see is Tim, and I don't recall him being bearded... unless he grew a beard, because that'd be totally fucking awesome.
A beard only helps reinforce the ROCK.
Edit: It could have been Kevin though. He is a bearded bassist... though not always lurking. I suppose Jim if you can count that as a beard (unless of course, he decided to become uber-metal and grow a grizzly adams).