No, no, it's not the lips- after all, even after a trip to the dentist when their lips are numbed by Novocain some of them are capable of lying. No, you can tell by watching them on RealScoop , a site that uses computer analysis of their voices to determine their believability level, with a bar at the bottom of the screen going from green to red. I can see one fly in the ointment: the software can only tell if the politician (or actor or entertainer or pundit- watch the clips, it's fun!) believes what he or she is saying- they could still be wrong. Judge for yourself from the clips.
TechCrunch isn't impressed, and points out other flaws- the party poopers- but they also say that RealScoop is going to cover the Debate Thursday! Accurate or not, it will be more fun to watch it there than on PBS!