This guy is shouting that he is selling Leaping Boots.
While in trade he will put the boots in window, then cancel the trade. After the 3rd or 4th trade, he will not put the Leaping Boots in but the Lizzard Ledeslens. Once he has your money he will log off, leaving you with crappy lvl 17 boots.
GMs don't appear willing to do much about this as I know 2 people who have gotten ripped off. If anyone knows who this guys main character is, feel free to post it, so the rest of the people on the server can make their life hell. In the meantime, beware this guy and shout that he's a con artist when you see him shouting.