Encrypted....The only no-go factor as far as I know is the firmware being locked.
Check that this has been done...
http://support.apple.com/kb/HT201065
If the seller can't do this then likely he is missing a password, then the "someone else" you refer to might well be "the previous owner".
Needless to say you should ideally witness this being done...if it has already been wiped and a clean install done then you won't know if the seller had the necessary password(s) or not...
We're meeting at a starbucks. So I should have time to sit down and check find my mac and also the firmware lock.
How do you check the firmware lock status? Boot and hold command + r, right?
EDIT: And yes, if either of these are enabled and he can not remove them in front of me, I won't be buying.
How do you check the firmware lock status? Boot and hold command + r, right?