three of mine are attached to paypal/RMAH right now... When you buy them just change all there information to your address... and attach account after.
None of the three were originally under my name.. And it's been 2 months on one of them, the others are under 1 month. All selling all funds being delivered to the same paypal.
What stops the original owner to contact Blizzard tech support after the sale and tell them that their account was hacked? AFAIR Blizz doesn't support buying/selling D3 accounts, so they'll probably return the account to the original owner. I know 20$ is not a big $, but still some people might try to scam.
IMO it's only safe when you are buying accounts from people you know...