Im not realy sure what you mean.
Do you mean like if someone creates a character in a character creator not ingame and gave it the best gear possible like you could in Diablo 2? if i dont remember wrong you couldent even go online with them anyway.
Also there is a reason why this game have the Online only DRM its so you cant hack the game and do those things.
What would stop Blizzard from making accounts, spawning the best gear, then selling the gear on the real money AH?
Nothing, really. If the sellers aren't shown on the interface, there'd be no way for people to know if Blizzard was or wasn't doing it (unless items show up on release day from areas higher than the highest character can access).
However, if it ever came out that they were doing it.... I wouldn't want to be connected to the project.
What would stop them from doing it? Probably a desire to not ruin their most promising new title.
If they tried to do it covert, it would inevitably leak because too many employees would have to know about it to make any real profit. Players would be in an uproar and sales would drop, especially expansion sales.
If they somehow prevent it from leaking, it would still have a negative impact on the game. They might make a quick buck but it would age the game far faster than it should. If you don't know what I'm talking about, see any of the numerous "why do casuals get full epix in 1 week?!!" topics that tend to pop up in the WoW forums. Difficulty and challenge make a good game, quick and easy rewards are fun in the short term but eventually ruin them.