This is a National Public Radio, Marketplace report.
http://marketplace.publicradio.org/shows/2006/10/25/PM200610255.html
Basically, this radio report (the link takes you to the transcript and you can listen to it also) details advertising/marketing's use of scent to draw in consumers and keep them looking at products longer, so they will be most likely to buy them.
Hey, I've been doing that one for years! You know, burning incense at festivals. Anyone who stops in my shop notices the scent, usually favorably.
And, real estate people have known for years that the smell of fresh baked bread, or a cinnamon simmering potpourri makes a house more attractive (on an unconscious level) to potential buyers.