That makes sense Judith. It's like an accident or a lack of control when too much of your own artistic sensbilities leak out into the image and corrupt the information. My example of that would be Modigliani. He painted lots of portraits but they all have the same oval face and long neck. So the viewer will never know what the subject actually looked like only the artists style.
So Iv'e changed my theory to any image in which you strictly limit the amount of your own individual style is not a self-portrait. Whenever you say I'm going to make an image that is a faithful and exact reprensentation of the subject, you are not making a self-portrait. The opposite would be any image ,no matter what the subject, that is highly stylized is a self-portrait. It would be an interesting project to make two images of yourself. One that is an exact non-stylized reprensentation of yourself- Not a self-portrait. One that is a very stylized, not exact image of yourself -A selfportrait.
It seems like photography would be less influenced by the leaking self phenomenon than drawing and painting would be. Maybe.

judith-that is something that was routinely addressed in some of my art classes- actually- one teacher would always bring it up in figure drawing.
it goes beyond artistry to me, more about knowing yourself more than anyone else.
the rule of thumb is spend more time looking at the model than down at your paper so you can avoid doing what is natural-> draw what you know, your body parts and so on