Shitweasel isn't my own. It may be a Hunter Thompsonism, though a cursory Google search indicates that "craven shitweasel" may be my own original constuction.

The online urban dictionary has an unsatisfactory definition here:

http://www.urbandictionary.com/define.php?term=shitweasel

Another Google search show that both right and left hurl it about with equal deftness.

Perhaps I'll see if that domain is available - and as Dave Barry sometimes said, it would make a great name for a rock band.