As the topic title says. What is a smell you figure few others reading will know and do you have any interesting stories there? Gross, pleasant, rare, feats you can do because of it*, did you do some science to discover it... all good for additional anecdotes here. If you are one of the many anosmia sufferers around here then a world of no smell is also interesting -- many will have shut their eyes/been somewhere completely dark, or worn headphones that block out all sound (possibly even done an anechoic chamber) but no smell is a harder one to pull off.
*having now collected books for several years I find I can tell the smell of books going back to the 1700s and periods, presses/locations (US/Canada, UK, Czech republic, France, Germany all being quite different in 1800s through early 1900s) and things besides. I don't know how well I would do in a blind test, and it works best in combination when I can see the paper as well, but I have opened many books now and been spot on with the age before I make it to the relevant page in it. I find the worst is probably late 80s and early 90s general interest books. It was never great at the time but seems now the binders, inks and whatever was used to treat the pages have an even more unpleasant chemical smell.
*having now collected books for several years I find I can tell the smell of books going back to the 1700s and periods, presses/locations (US/Canada, UK, Czech republic, France, Germany all being quite different in 1800s through early 1900s) and things besides. I don't know how well I would do in a blind test, and it works best in combination when I can see the paper as well, but I have opened many books now and been spot on with the age before I make it to the relevant page in it. I find the worst is probably late 80s and early 90s general interest books. It was never great at the time but seems now the binders, inks and whatever was used to treat the pages have an even more unpleasant chemical smell.