Am I to squeaky clean to understand the challenges of life?

I was reading an article where it talks about Newt Gingrich, who is a thrice-married, two-time adulterer, using that to say he is more normal in the eyes of voters than Romney, a man who has been faithful to his wife and kept his vows. The article quotes Gingrich as saying, "So, I think in that sense, it may make me more normal than somebody who wanders around seeming perfect and maybe not understanding the human condition and the challenges of life for normal people."

In the comment section of this article someone put a quote by C.S. Lewis that says....
“No man knows how bad he is till he has tried very hard to be good. A silly idea is current that good people do not know what temptation means. This is an obvious lie. Only those who try to resist temptation know how strong it is. After all, you find out the strength of the German army by fighting against it, not by giving in. You find out the strength of a wind by trying to walk against it, not by lying down. A man who gives in to temptation after five minutes simply does not know what it would have been like an hour later. That is why bad people, in one sense, know very little about badness — they have lived a sheltered life by always giving in. We never find out the strength of the evil impulse inside us until we try to fight it: and Christ, because He was the only man who never yielded to temptation, is also the only man who knows to the full what temptation means — the only complete realist.”

Now I didn't post this because I'm a firm Romney supporter. My interest in it actually has nothing to do with politics. What caught my attention was the attitude that if you've made good choices in your life and haven't given into the temptations that befall many people than you don't understand the challenges of life and the human condition. The quote by C.S. Lewis spells it out perfectly.