I'm inclined to agree with David Sirlin's definition of a scrub [http://www.sirlin.net/ptw-book/intermediates-guide.html]:
A scrub is someone who thinks there's only one way of "playing the game correctly", and then vocally exclaims that anybody who plays differently are "cheap", "honorless", "unskilled" or other similar things when he loses. Thus, even if someone's a better player than him, he can at least claim that he's got a certain moral high ground because at least he's not being any of the terms used above, even if he loses.The derogatory term ?scrub? means several different things. One definition is someone (especially a game player) who is not good at something (especially a game). By this definition, we all start out as scrubs, and there is certainly no shame in that. I mean the term differently, though. A scrub is a player who is handicapped by self-imposed rules that the game knows nothing about. A scrub does not play to win.