I would also like to have some ideas on the issue from vintage experts. I bought a partly used bottle of no 5 parfum at an antique store. It definitely doesn't smell as it should be, though, in my case there's much that does resemble more modern versions of no 5 that rather than a fake I suspect some deterioration. I too detect a sort of dusty amber, or more precisely a note of old dusty books, whether original or not I doubt. And I don't get the oomph of modern formulation, though the smell is extremely crisp and clean, and, after dabbing more properly, I do also smell some florals (especially jasmine).