I never read or experienced any evidence of eBay-sold AppleCare being a scam, though I did wonder. I ended up purchasing my Mac Pro AppleCare 3 years ago on eBay from a seller called memorymate. It cost $80, activated fine, and I eventually had to use it for a failing optical drive. There were no problems with the AppleCare, and it cost me a fraction of the cost had I have purchased from another source.