I don't think this is true. We had the Bay of Pigs, the 1973 CIA backed coupe in Chile, the Iranian Contras ...
Every administration from the time I was born and from the time my parents were born has been hopelessly corrupt. Obama won a noble prize and then became the first president to spend every day of his term at war (or I guess every day in office in an extended military engagement since America has not technically been at war in a long time because we like changing the names of things to pretend they're not true). That and he predator droned a bunch of people, passed a useless health care act, etc.
I'm not saying the current administration isn't corrupt. It is, and it's not just the puppet on top. It's all the industry that funnels money into legislative and executive branches. Neither Bush nor Obama went after the corrupt housing industry that caused so many people to lose their homes.
Citizens united didn't cause the corruption. Corruption has been legal for decades.