"Reading" faces - Can you tell if a smile is real or fake?

[Windbreaker]

I scored well in this....but honestly, I would not know if I would answer the same way twice if I had to do it again.

I think the tells I used:

A) Wrinkles around the eye. The more wrinkle, the more genuine.
B) Giggles. Have no clue why, but I find people giggling more genuine.
C) Their reaction after they go back to 'normal'. The faster their facial expression turns back to normal...the more it appears to be a fake.

I have no idea how accurate it is to use these tells in general...but seemed to work here.