I'm not too sure about this whole thing. I have 2 bottles of Creed from a reputable eBay seller: Millesime Imperial and Himalaya.
In my experience, both bottles are as they should be or better. I received a sample of MI from Aedes in the past and it was exceedingly disappointing. It lasted about 10 minutes and had no depth. I have not owned or tried a retail bottle of Creed, only samples from these bottles.
Naturally, experts will endorse buying Creed from authorized sources. However, I think it is possible to get a good bottle from overstock or "grey-market" sources. I feel I got two good bottles from eBay, but perhaps it was luck.
As far as the scent turning, I think it makes sense that natural ingredients will be more volatile. I think much of this has to do with expectations and perceptions. I like to think that fragrances age like fine wines: changing, yet developing a unique character.
I wonder what Creed has to say about this whole deal. Perhaps Grant will have an interview soon!