Personally I've never purchased a spoiled fragrance from a small store but I could see it potentially happening especially if they have a large stock and don't rotate stuff threw to much.
So this is your Kouros that smells off? http://www.basenotes.net/threads/249978-Vintage-Kouros
Go down to the images of the Kouros Box in this thread. Supposedly Kouros was slightly reformulated to some noses. Check the ingredients on the box for 2YFO2-2 or 2YFO2-3 at the end of the list.. the one ending in -3 is the one found to be a slight reformulation; possible its what you got?