The question is, why do we allow it? If you took the behaviour that is standard-pracitce for marketers and journalists and tried that with a friend, you'd get punched in the face. Somehow we shielded a few areas of our lives (like advertising, journalism, politics) and decided that it's ok to be deceitful in those areas.
If anything gets us is not us believing the ad, but just getting pumped with the nice visuals and subtle suggestions (so more subsconscius manipulation than convincing us).