Thanks Roger and everyone else for your replies.
This question is not easy to answer but in my humble opinion (after thinking about it since I posted this question) I feel the question itself has the answer in it. There are no rules as to how a photo should look. Yes, there are certain rules for paintings that was borrowed for photography but even painting has discarded those rules long ago with abstract art.
Everything is permitted as to how a photo should look, there are no rules and its up to the photographer to use this absolute freedom and express their feeling\thoughts.
In fact Robert Frank broke every rule of photography almost 60 years ago with The Americans and still managed to make compelling photographs, and here we're still buying the old nonsense about composition rules, tonality, sharpness and other purely technical matters.
People should just forget everything they know about how photos should look and then go out and look for themselves, at least that's what I plan in doing.