After publicly exposed across-state-lines patron of working girls David Vitter was re-elected, it was clear that having an "R" after your name insulates you to scandal, at least where the electorate is solidly Republican. It mattered little to Louisiana voters that the Senator was a regular at one or more "House of the Rising Sun," and not just down in New Orleans. Even the fetishistic details (diapers) could not drive him out of office.
By comparison (apart from the whole dereliction of duty, spending state funds, trespassing issues) Mark Sanford was simply a man following his heart, and recently, just bonding with his son (while trespassing, but still . . .).
The election also gives a sense of just how powerful Nancy Pelosi is as a Democratic demon. She really is the devil incarnate to hard core Republicans, a living symbol of everything they hate with a passion -- extending health care, strong women, San Francisco.
Of course, Republican infinite forgiveness does not work in competitive states or districts, as aspiring swinger (with ex-wife Jeri) Jack Ryan found out in Illinois, paving the way for the election of Barack Obama to the Senate.
As for Democrats, so far there seems to a double standard (Vitter hangs in there, while Spitzer must resign). But the Anthony Weiner case will be a test. If he runs and wins, maybe there's a similar syndrome of forgiveness among Democrats -- . (Though not the hypocrisy of family values Republicans having no problem with philanderers and interstate Johns.)