This one is very easy to do

You need a few hundrede gold for this one.

Make an alt account with a decent name.

Send you cash to your alt. Log you alt and find someone selling epic or other good stuff.

Negatiate a price and draw the money to the trade window. You must place the money before he puts the item

Quickly remove some of the money again and press accept. Like you agree on 300, and you quickly remove some so 30 is left (not everyone will notice)

Other part will put item and accept..

You saved lots of crash

Trick is he first sees that you put the agreed money (300) so while he drags the item you remove it some so it still looke the same (30)

Lots of people use this scam

Best of all, GMS dont do anything about this one..

Lol Gm's do care about this depends on wich gm the guy you scam reports to^^