excerpt below, more at link ... BPL is no different ;)
In writing his book, Lindstrom carried out his own experiment. He hired a family — called the Morgensons — from Laguna Beach, Calif., and filmed them as they had friends over from the neighborhood and talked about 10 specific brands they were using. Their mission was to frequently mention these brands without letting their guests know of their secret motive.
Lindstrom was skeptical at first, but then realized that word of mouth is extremely powerful.
"This simple family, they within three months were able spread the word of mouth to 15,000 people across California," he says.
In fact, it was so successful that "nine out of 10 [exposed to the family] definitely bought at least one out of the 10 brands."
Even after Gina Morgenson, the mother, mentioned the brand Kiss My Face for the 10th time, people didn't realize it was part of a setup. Lindstrom says that's because we spend so much of our time talking about brands that it didn't seem unusual.
"You and I are talking about brands 25 percent of our entire time. ... It has become such a big part of our lives, I would almost claim we would have nothing to say to each other if we can't talk about brands," he says.