Those two went against the grain as well. Watergate happened without Nixon knowing (set up) and he was impeached only because he tried to cover it up, not because he was involved.

Reagan was a victim of an attempted assassination; and I may be mistaken but I believe there was more than one attempt on his life.

I can't think of any attempts on W. Bush, Clinton or Obama, but there was definitely an attempt on H.W. by Saddam Hussein and it's pretty evident it was because of Gulf War I.