I have no problem with the Scammer - even though I don't really believe his failure to pay on a bet meets the definition of a "scam" - tag being applied to Matthew because he agreed to that in advance. I have a huge problem with the fact that Matthew was given the tag within hours while the Bitcoinica guys still don't have scammer tags after many months.
Historically, I think the fastest way of getting a scammer tag was to admit that you were scamming someone. Matthew N Wright managed to do that in theatrical style with the attention of a large chunk of the forum upon him, and theymos himself was amongst those scammed. If anything it's surprising that it took that long.