Marital Fidelity in Politicians

Do our political leaders need to me honorable men who avoid sinful behavior? My heart tells me they do. I want to have people in office who can hear the whisperings of the Spirit and can lead the people to do right. Book of Mormon talks about how quickly people fail when their leaders fail.

On the other hand, we have stories of evil kings being used for God's purposes in the Bible. 

Victor Davis Hanson wrote the following which was a useful encapsulation of the problem for me. 

I wish I could believe (because I want to believe) that fidelity is essential in a leader, but unfortunately history tells me that Charles Lindbergh was a better pilot and inspiration than his more moral rivals, that the wayward George S. Patton saved thousands of lives by his brilliance in a way the more admirable but limited Omar Bradley did not, that the randy Bill Clinton was a better president than the devout Jimmy Carter, and that recklessly promiscuous JFK was no worse and probably more effective than loyal Richard Nixon. But marriage has so many variables (the devout husband can be mentally cruel and indifferent, the noble wife can be a shrew, the publicly supportive spouse can privately forgo sex, the faithful husband can be lazy and a leach), and leadership so many contours (natural brilliance, rhetorical flair, stamina, courage), that fidelity in marriage simply cannot quite trump them all. Was the wonderfully devoted Harry Truman a better president than Dwight D. Eisenhower (who once or twice probably strayed with his chaufferess), and if so, was it because he never looked at other women other than Bess?