Attempting to judge a culture's morals, values, history and politics only through its popular media can be dangerous. The culture of a country is made up of the people within that country.
Melting pot cultures, such as the USA have very diverse cultures that span across a continent. Even more ethnic cultures, such as Japan, have a diverse cultural landscape made up of individuals. In some countries the popular media are owned by political parties, making them inseparable, such as the 1925 Soviet propaganda film Battleship Potemkin, directed by Sergei M. Eisenstein. In other countries films are made by a small minority of people that can place their own agendas into the movies that are made.
Using the American films shown in class to find both the good and bad aspects of American culture, we would find ourselves generally well balanced between good and evil, though these would not be entirely accurate for everyone in America. Americans are shown to be brave (Birth of a Nation, King Kong, High Noon), egocentric (King Kong, Bonnie and Clyde), smart (Invasion of the Body Snatchers), and cowardly (High Noon).
Is everyone in America going to leave a man to fight a bloodthirsty gang of robbers out for revenge alone? Would everyone in America sail to an unknown island and try to capture a gigantic ape? No, most would not; but, taken at face value, these movies and many others before and since, can give people the wrong impression about the cultures that made them, some more so than any book or news clipping.