All rational actors believe they can read a person.
The reality is we tend to believe what people say matches what they are going to do.
That is why traffic laws function so well–everyone agrees to them every time they get behind the wheel. We trust everyone is buying into this system that has been set up.
But much like driving on the road, we shouldn’t make quick judgments about the intentions of the other drivers on the road. Often times we mistake nice for good (and unpleasant for evil).