Kennedy wouldn't be elected today if the voters knew about his womanizing. He still was one of the best leaders America ever had.
I sometimes wonder where we would be today if it hadn't been for Lee Oswald. We probably would not have lost a war in Vietnam, for one thing.
Reagan wouldn't be elected if the arms sales to Iran and the bailouts of the S and L became an issue. Reagan was still a strong leader who did good things for this nation, but there were some negatives that the Republicans would like to forget, too.
There never has been a perfect president, and never will be.