Obviously, if you turn your head to look at the girls boobs next to you, you're gonna hear that in recording. To convince yourself, you stick your mics on your hat in binaural fashion and walk around the house. It's amazing how 3D it sounds.
In terms of standing dead still, of course that's not a big deal. You can shift around and maybe even move a little right and left to get away from talkers, but other than that, you're gonna hear the movements in how the balance is created between the stereo mics. Yeah, it can be subtle and some people may be more anal about this than others, but you can hear the difference.
Part of the problem is that the dynamics of a room can change significantly if you standing in point A versus point B and they may only be a few feet from each other. I tape at a place in pittsburgh where the dynamics of the room are can change HUGELY in just a few feet.
When I stealthed, I liked to have the mics on my hat...then if I really needed to I could take my hat off and leave the hat pointed forward while I turned my head to sneeze or whatever.