ORLYScum

A form of circular reasoning

"If X is scum, then his arguments are scummy. X is scum. Therefore, X's arguments are scummy."

This is an invalid argument. It's not a good way to persuade anyone else that player X is scum, except perhaps that it might draw attention to the fact that player X hasn't produced any good arguments or evidence in his favour. It might have value in terms of getting a reaction from player X or other players.