There is no perfect theory of persoanlity. This is a fact that can be explained by the diversity of personalities that we encounter throughout the world. Each human being has a different personality that until today, it has not been decided whether it has a genetic or environmental origin, nor is it known for sure what influences these personalities, not even if they remain or can be modified over time. Even if an individual has a well-established personality, we know that it can change between situations.
All these factors, show that the persoanlidades are composed by innumerable different variables, what hinders the establishment of experiments that give concrete results and allow a perfect and totally credible theory.