They say a picture is worth a thousand words. With the human face it's even more revealing, especially the eyes.
Politicians, if you've ever seen a professional one up close, have almost a waxen stiffness and sheen to their phony, memorized expressions. Most public and power characters need to be caught off guard to reveal their true nature, but it's not necessary. Usually it's in plain sight.
The eyes are the 'windows of their souls', while their expressions can also intermittently give away their true nature.
Here's a quick selection of some current, and a few past, leaders or power brokers.