The more experienced you are the more you "know" what you got.
That being said. the difference between "experiencing" a scene, or especially a person, and what was captured on the film or card is often a long ways from what you thought you got.
People are an enigma to how they come across in film/digital. You're never really sure although you know you got the elements right like lighting etc. you really never know how much the camera 'loves' them.