Different people has different sensitivity to different substances.
Take musk. Musk is an organic substances coming from the glands of a few animals. It's one of the most common base notes in perfumery. Since perfumes became a mass market product, there aren't enough musk deers in the planet by some orders of magnitude to fullfill the demand.
So they created "white" (synthetic) musks. Problem is most persons are anosmic to this one or that one white musk. Also white musks are not exactly biodegradable. Perfumists make cocktails of them to make sure you will feel some of them. A few people (sigh!) are anosmic to every polycyclic and macrocyclic musk.
And this is for substances that their explicit mission is to be smelled.
There are newer alycyclic musks much more biodegradable and most people can feel them. See Romandolide, Helvetolide, Rosamusk, if you're curious.
Take musk. Musk is an organic substances coming from the glands of a few animals. It's one of the most common base notes in perfumery. Since perfumes became a mass market product, there aren't enough musk deers in the planet by some orders of magnitude to fullfill the demand.
So they created "white" (synthetic) musks. Problem is most persons are anosmic to this one or that one white musk. Also white musks are not exactly biodegradable. Perfumists make cocktails of them to make sure you will feel some of them. A few people (sigh!) are anosmic to every polycyclic and macrocyclic musk.
And this is for substances that their explicit mission is to be smelled.
There are newer alycyclic musks much more biodegradable and most people can feel them. See Romandolide, Helvetolide, Rosamusk, if you're curious.