Turns out that Martin Lindstrom did a very similar experiment for his new book, Brandwashed. With a budget of $3 million dollars and a professionally casted family they repeated the experiment. I didn't get around to reading his book yet but apparently the family did manage to influence a significant number of friends to buy products. While having no idea of the true objectives of the family.
Martin Lindstrom thinks that we can expect companies applying the stealth marketing strategies from his experiment more and more in the future. But he also argues that brands should become more transparent and honest than ever, if they want to survive in our hyper-connected world where consumers can reveal any dirty marketing that is played on them or broken promise with a simple mouse-click. Authenticity and transparency are key values for companies that want to apply the power of word-of-mouth in their advantage.
Source: Insites blogHonesty over trickery. Or that's at least what it should be!