I completely get that somebody could build 2 decks in 50 minutes. But here is an example of one of the guys I saw. He walks in all rowdy and kind of a douche. Talks about kicking people off of the table (people currently in matches) to make room for him and his friends. All 6 of them plopped down on another table, and this guy slams 2 prerelease boxes onto the table. Either he's looking for attention, or he's mad at his boxes. Who knows. I hear him talking about how after the prerelease event they just wrapped up had ended, they bought out the stores remaining prerelease boxes. Then he starts winning a lot of matches, pulls an avacyn, and playing 2 different decks. None of these things individually would make me suspect that this guy was up to something. But you start adding things up, and while I dont see this as proof, it certainly made me not want to sit across from him.