I agree and think its fascinating to see portraits of a person done by a number of great photographers, each showing THEIR perception.
As I've stated before on the issue of portraiture, is the difference in who is paying for the portrait. If the subject pays its a far different animal than if a magazine/publication pays or no one pays.
The whole dynamic of flattery/ego enters the equation when the subject is the one with the money or power behind the creation of it.
As with almost all aspects of human interaction when you "follow the money", you get a far better picture (pardon the pun) of intent and influence behind everything, and a portrait is no different.