Smile spotting - can you tell the difference?

I was taking a smile spotting survey that I found from Kathy Sierra's blog (good reading) and I know a little bit about how to tell a fake smile from a real one (in theory) and I thought it would be fun to see how good I was at it.  At the beginning, I didn't do so hot because I was thinking about what little I knew about eyes and the like, but once I gave in and let myself intuit I got the rest right (although I wasn't very sure on some of them).  At the end of the survey, there are tips on how you can reliably recognize fake and real smiles.