Let us suppose, hypothetically of course, that a person has an account and a presence on a non-PvP shard...errr...server. Some characters are Horde. Some are Alliance. It is the intent of Blizzard that Horde cannot talk to Alliance, trade with Alliance, group with Alliance, make friends with Alliance, breed with Alliance, and so forth. Let us suppose that on this account, Mr. Horde has something that Ms. Alliance can use. No way to mail it, etc. But there is the Neutral Auction House. Would it be evil, detectable, bannable, frownable, if Mr. Horde were to put something up for auction, log off, log on with Ms. Alliance, and buy the item? Not that I know anyone who would wish to do such a thing.