You did see it was a CoreDuo machine, so it's the 1st generation MacBook Pro, nowhere near new?
The listing is well written, doesn't scream 'scam'.
Possibility there is some fatal flaw with the machine, but with Applecare...
If they have registered their Applecare, they should be able to show you the serial number on the Applecare site verifying the warranty.
If it is real though, it will have been sold in the first 5 minutes.