I guess you could say a pro is that gullible people will believe you, but that's an unethical pro. The cons are that it usually causes much controversy in a society where there's not supposed to be a bias in the government. Propaganda in its true form is never a good thing. It is unethical in the sense that it takes advantage of people who are too lazy to do research and quick to believe what someone tells them. One example I like to use is many of these independent "news" websites. On both ends of the political spectrum, left and right, you find websites that have articles so heavily weighed down with that wings propaganda that true news becomes less and less visible. Occupy Democrats is one textbook example of that.