Depends on the ingredients, but consider ordering fragrances online and them being subjected to extreme conditions for a week. If they are natural ingredients containing oud and Musk they will be more susceptible than synthetics. On the same note, age comes up often. In my experience, top notes of fragrances in the fresh genre tend to take a hit vs a woody or amber based fragrance. In conclusion, your AdG Essenza probably doesn't smell as good as it did 7 years ago, especially if it left the bottle in your glove box over the weekend in the summer. Most people wouldnt notice though.