Suppose you, in the course of your travels, find yourself in the midst of a new culture — new people, new customs, and new ways of doing things. In your efforts to understand this new culture, you might talk to people, observe customs, and/or try to learn about it by studying/viewing documentary sources.
Or you could just turn on the TV and watch their advertisements.
Few things are more representative of what a culture values than the objects it is prepared to spend money on. What people want is often a surefire indicator of what they are. The advertisements you watch will show you not only the objects of their dreams, but also the way they visualise these dreams and the metaphors they associate with them.
People will lie in books, they will let their biases creep into their documentary films, they will even overstate the importance of their customs. But there will be few or no lies in what their ads promise them. Those are the things that define them and what they want to be.