EDIT: Just noticed your post above. That really sucks.
This is true.(guess not, anymore) I got my WoW account attacked hacked (lol) (somehow, I never found out how since I only played the 1 month trial for about 2 weeks and didn't noticed from this point until about 3 years later when I returned to play Starcraft 2 and loaded up my WoW account for fun... seems nothing on my Bnet account was changed, but I definitely lost control of my WoW account... I think I fell for some phishing attempt at some point way back when I wasn't as wise). Despite this, I went onto my account one day to find it full of characters with website names. I contacted Blizzard and they asked me for receipt and/or a picture of my serial and game. While I am not a big fan of Blizzard (like Diablo 2 and Starcraft 1/2), they take this stuff seriously. On the flipside, this is why I would never trade for a Blizzard key, as there are many scammers that will sell you one and claim to Blizzard you stole it.
I also was semi-scammed (misleading trade) by someone on the Steam forums. I almost gave up on trading completely until I found this website and the Neogaf Steam topics. Good people in both places, but you cannot beat CAG's setup. There is no benefit of being a liar here, as even 1 negative could probably have an impact. When the majority of people are posting here with 100%'s, it really stands out even if 99%. Most of the people here with negatives, as I always check when thinking of trading with someone less than 100%) were probably screwed over in their trade that resulted in a negative, or at least some sort of miscommunication.
I look at this website several times during the day and I would trust $10 with someone here before I trust it to my own sisters (yeah...).
Yeah, this is why I am really surprised with Blizzard. When I use to play wow, I've seen guildmates get hacked and lose their accounts and stuff and they had to provide proof of purchase and such, which is why I am so surprised Blizzard is doing this to Severose