I had reported this once almost a year ago, but it seems Aeriagames doesn't want to fix this (Although I did get my Alice) and I just checked if it was still working. Basically allows you to put items/money into the trade with a different amount or items that doesn't exist at all, which will appear to both sides and not just clientside. In the end, you could buy an item from somebody with like 99999999999999999999 gold, but he still receives only 1 gold or none and you get what he had put into the trade window.
All you have to do is to record the packet when you put an item into the trade window (or gold) and edit the amount in the packet, it's best done if you do this with a friend first and then send the packets during the trade with somebody else. Do it with WPE or something else you're familiar with.
I'm sure somebody must have found this out already and posted it somewhere on the internets but not here.
