I've noticed that some fragrances seem to be sold for many years after they were discontinued, for example Bowling Green. You can find it everywhere. Have these bottles just been sitting around for years? Does this mean they are already potentially going "bad" at the time of pruchase and/or have a greatly reduced shelf life?
To be honest, it depends on how these bottles have been stored. If they have been stored in a warm bright environment, they are more likely to be 'turning' than if they had been stored in a cool dark place.
I have a vintage Caron perfume from the 1920s and it still smells fantastic, although the top notes are a little wobbly, the drydown is amazing.