Bet you don't know why the cosmetics and perfume area of a department store is often one of the first you'll encounter upon entering. According to Paco Underhill's new book, Call of the Mall, the tradition dates back to the days of horses and buggies when the perfume served to counteract the equine odors from outside.

Underhill, who also wrote the bestseller Why We Buy: The Science of Shopping, focuses his new book on malls and how we use them. The insights in the book are useful for investors to help in understanding what we see when we look at the many potential investments located in a mall. These investments would include, for example, stock in Gap (NYSE:GPS), Abercrombie & Fitch (NYSE:ANF), EsteeLauder (NYSE:EL), Sears (NYSE:S), J.C. Penney (NYSE:JCP), Nordstrom (NYSE:JWN), and Federated Department Stores (NYSE:FD).

Here are a few tidbits from the book:

  • Why are restrooms usually located at the end of long, dingy corridors? Because their placement was designed by real estate developers, not retailers.

  • When should a shopper ideally be approached by a salesperson at a cosmetics counter? Not in the first 30 seconds, or the customer will be scared away. Better to wait while the customer looks around, then pounce once he or she raises her head.

  • When shoppers take a pair of jeans to a dressing room, 65% of men will buy the pair, while only 25% of women will.

  • Fully 90% of shoppers turn to the right when entering a store. Higher-margin items should therefore be on the right of the door, not to the left of it.

  • Malls are where 14% of our nation's retail sales ($308 billion) are generated.

  • American consumers spend more money on candles than lightbulbs. (So much for the march of progress and the industrial revolution!)

Underhill offers good news for retailers and investors: More profits can be generated at malls, if some changes are made. He makes many suggestions in his book, such as coat-check services and better navigation aids to help shoppers find their way around the mall and back to their car. Another suggestion (warning -- some stereotypes ahead): better seating for men, who are often at the mall to spend time with their family or just be out and about, compared with women, who tend to be all about shopping when there. Make the man comfortable, and the woman can shop longer and buy more. Oh, and how about shopping carts in malls, so people don't have to lug so much stuff around?

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Longtime Fool contributor Selena Maranjian does not own shares of any companies mentioned in this article.