People who play games become predictable when winning matters more to them than truth.

Someone who has to win will eventually distort things to keep winning, and distortion is a pattern rather than a single event. Once you know that accuracy is not their priority, you can predict them: they will take whichever position keeps them ahead, regardless of what they said before. The manipulation stops working once you have understood the rule. Their need is the thing that makes them readable.

Watch for people who never concede a point, even a small one. Stop treating their claims as positions to be argued with and start treating them as moves. Then decide whether the exchange is worth having at all.