It's actually a pretty good simile, come to think of it. The back of my hand is one of the most familiar sights to me, since my hand is always attached to my arm and usually with the back turned toward my face. Like right now, typing - I can see the backs of both my hands. But the back of the hand is such a commonplace sight that the person attached to the hand doesn't even think about it - certainly doesn't study it or memorize it. With my hand held out of sight, I'd be able to give a rough description of it, probably forgetting or misidentifying the location of a few scars and spots... Or I could pick it out of any lineup of hands. Not sure how you'd make a lineup of hands, but I know I'd recognize mine.

Typing with your nose? Okay.....