Spot The Fake Smile
Results
You got 16 out of 20 correct

Interesting, since I was focussing almost purely on the mouth. I can't read peoples eyes at all. Plus I got screwed on some as I double-clicked on play and couldn't watch the video at all (yes I'm an idiot).

Most people pull their lips back from their mouths with a genuine smile and move their head. If the lips stay together or they overbite them it generally isn't genuine. Or so I reckon.