The problem lies in the fact that there are some clever people out there who found out that item stats are determined when it is dropped, not when it is identified. So the game client must store those stats in memory somewhere. Writing a program to read that space in memory would be .. lucrative. You could tell which ones were going to roll good and roll them and sell them, and tell which were going to be garbage and sell them unid.
I was reading somewhere that people are doing quick IDs right before they actually ID (scripts) and finding garbage stats then selling it off.
They keep the good ones.