Your smile can be your most attractive feature. It doesn’t mater what the rest of you looks like, if you can spread a huge smile across your face, it will make observers feel warm. This is quite an attractive human trait. But does it matter if your smile is fake or not? The Textbook Human will grin, and bare the truth.
One amazing thing about people, is that we feel the emotions of other people. We do this via facial expressions, one form of non-verbal communication. So, our raw expression of happiness, joy and excitement through a smile, are perceived by other humans quite easily. And because most humans have such hard wired empathy, we also feel and experience the conveyed emotion. Psychologists call this “Affect Display”. Interestingly, this is why some people prefer to watch sport on TV. The close-ups of athletes faces during intense competition enables observers to feel the intensity of the moment. And, some Mimes have their Affect Display down to a fine art.
But how often have you faked it? Faked a big smile for a photo to pretend you were having a good time at that instant. Or faked amusement to a terrible joke so you could get along in the long run. Or used it to simply ’sell’ an idea to someone. I have, a lot. 
What I want to know is if Faking it, is as successful as pulling out the real thing? To answer that, a person would have to ‘feel’ as if your smile was not 100%. Or even, know that you you were actually faking it. But the problem is that detecting a fake smile is not as easy as you may think. As a human we have become very, very good at this particular form of Affect Display, or non-verbal communication.
If you think you can detect a fake from a genuine smile, then please take this little test on the BBC Science and Nature site. It will ask you two preliminary questions, then you will be given the chance to test your skills. Link.
I scored a modest 13/20. I think a lot has to do with whether you know that person. And having a real 3D person helps to. But as the interesting end results state, we actually do use different muscles for real, and fake smiles. Genuine smiles, are generated by the unconscious brain after emotions are triggered by certain stimuli. Fake smiles are simply a communication trick, used by most people as a social tool.
I got 14/20. Lashed.
One thing we noticed is that people look away with the genuine smile and stare at the camera more so with the fake. i got all but one of the fake ones wrong, most of my mistakes was thinking peoples real smiles were fake.
18/20 here, imo it’s all in the eyes.