No fewer than two merry little exploits are currently stinking up the Diablo 3 auction house. The first is a bug that, by fiddling with chat windows, allows you to see precisely how many special properties an unidentified item has. This matters because it allows unscrupulous auction house sellers to pawn off their weak unidentified items while identifying and selling their more powerful items as normal. In short, as the Reddit user who went public with the problem suggests, avoid buying unidentified items on the auction house until the exploit is fixed.
The second exploit was reported by Diablo 3 Markets, and allows grubby auctioneers to buyout items at their bid price by quite literally swapping the buttons around using a hex editor. Both are faintly alarming revelations, and will hopefully be remedied with a deft hotfix. Blizzard are meanwhile battling with gold farmers who continue to undercut their gold prices.