I should never cover politics. I can't distingish a fake smile from a real one.
Take this quick test that the BBC has posted online, based on the research of the University of California's Paul Ekman.
You play 20 videos of people smiling and tell it whether their expressions are natural or not.
I got more wrong than right.
Afterward, it will tell you how to spot the real thing. I won't give the secret away, but it's something to keep in mind.