From his body language: "I'm lying." He's shifting his weight from foot to foot -"Which way will I go, if I need to run, if you don't buy what I'm selling? I'll keep you guessing." When looking at the people he's talking to his eyes dart to the left. Even with his left eye being lazy, you can still see this. He's actively referencing the creative (left) part of the brain - used to create a lie. When looking right his eyes dart rarely: "I'm returning to the script I've heavily rehearsed."