I hate it when people are walking behind me. I have stopped and looked into a window (window shopping) but kept myself kind of sideways, not with my back totally facing out.
I have a pet peeve about resturants. EVERY time I go into one and they sit me they put me facing away from the door. I just ignore where they put the menu and sit facing the door. When eating with friends or family they will nearly always assume I want to sit with my back to the door. I never do. I have not wanted to sit with my back to a door since 1989 when I was working at a prison.