We're policing the world because we're able and want to. Is there something wrong with that? I'd say the only U.S. special interests or agendas are in response to other nations. Nothing "evil" or what have you here.
You might point out that the Iraq War was. For oil? We can't get oil from Iraq without getting shot up. Yes? Blood for Oil? I disagree. Of all Bush's mistakes, blood for oil isn't one of them. No, Iraq was a strategic mistake and an intel mistake, nothing more. Also, most of our foreign bases are on scattered islands, unstable nations, or nations which we fought/helped fight and then built bases on.