More information here on PBS program "The Persuaders" http://www.pbs.org/wgbh/pages/frontline/shows/persuaders/etc/synopsis.html
One of the original book on Public Relations by Edward Bernays
Wendell Potter author of book "Deadly Spin" describes the practices of public relations here
Public relations is a communication tool. It is like technology that can be put to good use to help people or it can be used to manipulate them for self serving purposes.