I was reading Hacker News comments about the trademarked scent of Play-Doh. I never thought about the smell of Play-Doh much, butit did occur to me that it has a unique scent. But as is often the case, the HN comments that jumped out to me were not directly about the topic. I quote HN user gambiting:

For me nothing beats the smell of Pokemon cards freshly out of a booster pack. I can recall that smell at a whim even though I haven’t opened any packs in years.
I probably have not opened a booster pack of Pokémon cards in more than 20 years (although I have played the Trading Card Game in other formats). But like user gambiting, I can remember the smell and the feeling of freshly opened Pokémon cards.