Every single bitcointalk account sale that I have escrowed so far has been returned to the original owner after the escrow was eventually released.
Wow, I could imagine some account sellers will claim to have been hacked after the trade, but I couldn't imagine there are so many greedy people...
After the second time it happened, I started responding to account sale escrow requests with the message posted earlier in this thread.
Once I included those requirements in my response to escrow requests, people stopped wanting to use me for account sale escrow.
So, when I say "Every", what I really mean is "Both", although it is interesting that nobody is willing or able to meet my requirements. I suspect the funds being locked in escrow for 30 days does a lot to scare them off.