In following the previous post, I will also suggest that President Nixon did more for this country than many people realized then, let alone now. He allowed people to see the difference between the president, and the Presidency.
It is that difference that, perhaps, caused the topic question to begin. There is a tradition of honor and distinction that the Presidency bestows upon the president. While corruption and scandal are not new to presidents, in almost all cases, the president elected to the Presidency has risen above themselves to make their tenure, if nothing else, an honourable one. Simply look at the records of presidents (both pre-Presidency and in-Presidency) such as Ulysses S. Grant, William Howard Taft, or either of the Roosevelts as exemplars of this perspective.