“Guilt is anger directed at ourselves.”
—Peter McWilliams
“Guilt is always jealous”
—John Ray
“The guilty think all talk is of themselves”
—Geoffrey Chaucer
Once you realize what you are seeing, it's very easy to know when lies are being told to you. Even when the person isn't speaking, their guilt oozes out of them as if willing itself to be revealed. All truth will find its way out. It is the way of things.