Patrick McManus, who wrote for Field & Stream, had a theory on how to bring new guns into the house. At a certain point, instead of your wife knowing that you have 6, or 8, or 10 guns, they just become "all those guns". When you get to that point, you can just bring them in anytime and not be noticed. He even had an expandable cabinet so there were always the same number of empty slots.
I think that same theory would be applicable for shoes as well!