My favourite portraits are those which depict character, not just appearance. C16th swagger portraits are perennial favourites (as are the Holbein studies of the More family), along with The Holy HCB and the rest of the photographic canon. I don't claim to reach such heights, but I find this style of photography much easier with people I know - if only at the editing stage where I can spot a characteristic look.(posted 8637 days ago)Conversely, strangers are much easier to turn into symbols, be it |bermensch or everyman. Such pictures are not portraits as such, but instead depict a mood, an impression or a state. They are mathematics to the true portrait's physics: one grounded in a definite physical reality, the other inhabiting a more abstract sphere where self-reference is the only mode of judgement.
I find the second sort of image is much more easily spoiled by minor details than the first. The difference between nearly-right and just right is enormous, and for me at least tends to be felt rather than consciously observed. I've been accused of over-analysis when trying to why that is, so I'll stick to the touchy-feely 'I know it when I see it' criterion for now.