I tend to agree with this as well. Just to check, I tested my own Leverage fic, Bad Habits and Dumb Luck (http://laceymcbain.livejournal.com/238358.html), and while there are a few physical descriptions in context (Parker's blond ponytail, Hardison's large dark hand, Eliot flipping hair out of his eyes - which doesn't necessarily imply his hair is long) ... I tend to assume I don't have to provide as much description because people know the characters. It's an interesting phenomenon, and I do think it's particularly prevalent in tv or movie fan fiction because we've got the actors to base our visuals on.