Violet is now considered a relatively cheap, simple, and old-fashioned scent. It's definitely old fashioned, since it's been popular forever, but the origin of its popularity is violet's amazing ability to take away a person's sense of smell.
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It's always gratifying to come across an explanation for something you have vaguely wondered about as a child. I read several books growing up in which the scent of violets was associated with a certain kind of magic. This was because, like illusionists' tricks, it was there one moment and gone the next — only to reappear later, as strong as before. This pairing was well chosen, because I recently found out that violets quite literally do have that magic property.
There are plenty of scents that we become accustomed to over time. We smell a perfume that gets spritzed on us intensely for the first five minutes or so, less so over the next hour, and finally we tune it out like we would any constant stimulus — the feel of our clothes against our bodies, the exact shade of artificial lighting at work. Violets are something else. They can't be entirely tuned out.
Violets get their scent from ionone. It's an extremely sweet scent that many people describe as also being dry. "Powdery" is the word that's usually used. Another word is "ethereal," or "ephemeral." After stimulating scent receptors, ionone binds to them and temporarily shuts them off completely. This substance cannot be smelled for more than a few moments at a time. After that, people go anosmic to it. Then, after a few breaths, the scent pops up again. Because the brain hasn't registered it in the preceding few moments, it registers as a new stimulus. Although plenty of people don't like the scent of violets, they don't constantly overpower people, and they don't fade out. They just disappear and come back, like magic.
Via The Secret of Scent, NCBI.