I think the trick is to fool the subconscious. Your brain takes in 1,000 visual details and puts them together and they add up, or your lizard brain throws up red flags because something isn't right. Something doesn't make sense. An obvious example would be the cut in a Submariner's bezel where the insert snaps in. You can smooth the outer edge so the teeth aren't so sharp, but the inner edge sitting right above the insert should be smoothed over from years of wear too, right? Check these pictures, my Red Sub when I got it, and then after some extensive but very mild ageing. Check the before and after on the bezel teeth and the cutout, it's rounded over on the top and you would never have noticed that... but your subconscious would.