If there were internal Facebook calculations about the humanity of the user, then there would be no fake users using openId on your client site. Facebook would already delete them.
You can check the checked field of the Graph API object of the user.
A user is considered verified if she takes any of the following actions:
- Registers for mobile devices
- Verifies your account via SMS
- Entering a valid credit card
You might want to play politics, as some sites did, you need X nbr friends, have a pic profile, etc.
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