We, humans are like sponges and soak up what is in our surrounding, unless our parents take care that we get less of that kind of addictive stuff. Music in commercials is intentionally pleasant and melodic so that we resound with it and the messages sink in - it's a hook. But even if you care that your child gets as little as possible of such messages the time of schooling comes and the peers pressure with it. Children are not neccesarily resilinet enough to withstand the peers pressure even if its unspoken.