John Edwards' and John McCain: Why Does McCain's Affairs Get A Free Pass?

This article makes a great point: why does Senator John McCain get a free pass on all of his affairs and antics with women and Miss Buffalo Chip, and Senator John Edwards gets damned?

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Now, we get to the most relevant question - if John Edwards' political career is done, why isn't John McCain's? John McCain had a well-documented affair on his first wife, with his current wife. He has admitted in the books he has written about his life that he ran around with several different women while still married to his first wife. And don't forget that he left her for a younger, richer woman - multi-millionaire Cindy Hensley who is now Cindy McCain - after she had been severely hurt in a car accident.

So, why are McCain's actions any more excusable than Edwards'? Because it was thirty years ago? Does that wash it away? Will we be fine with Edwards running for office again in a couple of years because then it will all be in the past? What is the statute of limitations on an affair?