Before these presidents had lives as presidents, they had lives as people. They really are just people. People sin, make mistakes, have regrets, are loved, and are admired. No matter what kind of life a president lived before his or her presidency, imperfection will always remain.
It doesn't belong to man to direct his own step, as it reads in the Bible. If we are waiting for a man or woman to rescue us from ourselves then we must not hold our breath.