I am almost cover to cover with Rachel Herz’s SCENT OF DESIRE. I will try to surmise a deduced hypothesis that would have notable implications for the business of branding:
“An original scent when paired with an emotional event will (when re-introduced) at a later date, time or location elicit the same emotional experience (in varying degree) even in the absence of all non-olfactory cues present at the original event.”
This is true for both positive and negative events. Take 9/11 as an example. For weeks after the terrorist attack, a unique scent pervaded the air (not intrinsically bad smelling) which elicited no emotional response from people living outside of New York (per research findings), however produced strong emotional reactions in inhabitants of this city who were also present at the time of the attack.