Reading people is a tricky business.
While there are methodologies like “body language” to size up an individual in a general way, we humans are just too dynamic to be nailed down specifically. After all, people can display like behaviours with entirely different motivations.
It can be pretty hilarious (at times irksome) to have others playing psychic or shrink by interpreting your actions in a particular situation and conclude that you belonged to a certain character type.
It gets worse when they extrapolate that assumption to other aspects of your life. They will predict your actions in some hypothetical situations, and provide themselves with “evidence” (in their mind) based on their own biases and past experiences. Once formed, there is little one can do to dislodge them from their presumptous hypothesis.
Just because we can see the pool of water, it does not mean we can know the shape of the ice cube.