That incongruity probably led to the 2006 backlash against scented ads in San Francisco. As part of a "Got Milk?" campaign, ads in San Francisco bus shelters were imbued with a chocolate-chip-cookie aroma. The idea was to make people crave milk. They didn't. Complaints poured in, and the aromatic milk ads came down after just one day.
Commuters just didn't understand why they would smell baked goods out there, says Rachel Herz, a visiting professor at Brown University and author of
Even with all the ongoing olfactory research, much about odor remains mysterious. Chemicals with different structures may smell similar, while those with nearly identical structures can smell completely different. That's a particular challenge to scent manufacturers trying to design the perfect scent. "If you take a novel assortment of odorous molecules, we cannot predict what that will smell like," says Northwestern University neurology professor Jay Gottfried. "If we mix amyl acetate -- a banana smell -- with eugenol -- a clove smell -- there are no rules to say how the mixture will be perceived."
Gender and experience, context and memory determine how an odor molecule is interpreted. When Herz had subjects sniff something identified as Parmesan cheese, they liked the smell. A week later she presented the same odor, telling subjects it was vomit. They found it revolting.
With so much ambiguity and sensitivity surrounding our olfactory systems, scent marketers have considerable responsibilities, Vogt says. They should not put their products in public spaces like bus shelters or spritz consumers without their invitation. And even though reputable scent marketing companies in the U.S. use approved fragrances, Vogt acknowledges safety concerns with foreign products; the Scent Marketing Institute is now establishing industry standards.
Even so, companies know there will be complaints -- Vogt recently received an e-mail with a subject line that read, "You are making us sick." A vocal population considers itself chemically sensitive, and scent marketers have already become a target elsewhere. Halifax, Nova Scotia, has declared itself a completely fragrance-free city. "In some Scandinavian countries, they're legislating against letting vaporous scents into the air," Santandrea says. "We're going to have legislation against us. But if the scent doesn't cling to you, we have a right to do it."
Santandrea insists that scent marketing helps consumers by giving them information. "We're democratizing scent," he says. "Shopping is merely hunting, and in the past when we hunted, we used our noses to inform us of what we were coming to."
At least for now, practical limitations remain. With many different smells mixing in the mall, the results could quickly become unpleasant. After 15 minutes or so, the nose adjusts to a scent and stops perceiving it. And when you go from one scented store into another, the fragrance of the second store may seem distorted to you, or hardly smell at all.
Still, efforts to introduce scent to everything seem irresistible. A few years ago we almost witnessed the release of iSmell, a "personal scent synthesizer" that would have released odors from scented Web sites and e-mails out of your computer. Although the company involved fell victim to the dot-com bust, the technology is available.
Motorola has a "smell-o-phone" in the works (so you can look forward not only to hearing the conversation of the person next to you but to smelling it too.
Those kinds of applications, Gilbert says, likely hold the key to scent's future. "There will be a breakthrough in a popular culture application -- clubs, concerts, maybe scented artwork," he says. "Maybe then there will be a quiet revolution and scented ads will be no more ominous than billboards in Times Square."