You did it! We figured this one out! It is a truth universally acknowledged (by me for certain) that the Bitchery pretty much knows everything, and really, it's true. Scroll down to see the solution for this HaBO - and many thanks!
This HaBO is from Elizabeth, who wants to find this romance:
I need help finding this old Harlequin romance from the late 90s:
The main female character’s name was Nikki and she was an olfactory scientist performing research on how the brain reacted to various scents, similar to how pigs find truffles in the woods. She was specifically trying to research if voles, or hamsters, could make bonds through scents. She sets up an experiment where she inadvertently meets our male main character who is interested in her research, but for his own business interests, which are to use scents in cologne that will help men appear more attractive to women. Because the MMC was blindfolded during their first meeting he doesn’t know what Nikki looks like but Nikki cannot deny her attraction, or chemistry, with the MMC, and arranges a night-time rendezvous with the MMC. These late-night rendezvous continue after the MMC hires Nikki to work on his perfume. The MMC eventually figures out that Nikki is his late-night lover and attempts to woo her despite drama and rivalry at the office.
I love this story and have re-read it multiple times throughout the years, but have lost my latest copy. Please help me find this book!
I feel like there is going to be a handful of people who want to pick this one up!

Oh boy this has big time Harelquin Temptation/Harlequin Love & Laughter vibes. I thought it was IRRESTIBLE? by Stephanie Bond, but that involves a woman taking a pill as part of science experiment, not a scientist and perfume making hero. Maybe even a Harlequin Blaze, although those started in 2001
I feel like this pheromones/love potion type plots were very popular in the 90s.
Grrr! I feel like this on the tip of my tongue. I haven’t read it, but I can almost picture the blurb.
Hope someone else gets there.
“The Twenty-Third Man” by Peggy Nicholson. This was a Harlequin SuperRomance from 1997.
Synopsis: “Reese Durand has developed a new male scent, Irresistible, which is supposed to be a pheromonal solution to attracting women. It will make him millions–billions–if it works.
Unfortunately, it doesn’t. Which is why Reese is the twenty-third man standing in a science lab corridor, waiting to test a…”scent.” If graduate student Nicola Kent has indeed discovered the secret of sexual attraction, he needs her research. Hell, he needs her!
What he finds is a female tester named “D”–and immediate and overwhelming sexual attraction. But he can’t see her because he’s blindfolded. Now Reese needs to track down two women–Nicola for her formula, “D” for lust–or is it love?”
Amazon US has 2 copies of this at $1.99 (I guess second hand?). If Elizabeth wants one, I’ll get the other and start a SB lending library …?
Great job @Jenny!
This used to be available as digital editions… I guess we should all bother Harlequin to re-release it!
@Jenny, that’s it! The Twenty-Third Man!! Thank you so much. <3