John McCain, who cheated on his injured first wife and eventually married his mistress. That didn't stop him from being the GOP's 2008 presidential nominee.

Sen. David Vitter of Louisiana, who despite having been caught up in a hooker scandal (in which it was revealed he had a fondness for diapers), retains his senior Republican positions in the Senate and is a lock to be the GOP's nominee for his seat in 2010.

Rudy Giuliani, who cheated on his first two wives, and even used public money and policemen to carry on his affairs (including having cops walk his mistress' dog). Yet Giuliani regularly appears on Fox and other networks as a national Republican mouthpiece.

Newt Gingrich, who, as Steve Benen notes, "obtained his first divorce in 1981, after forcing his wife, who had helped put him through graduate school, to haggle over the terms while in the hospital, as she recovered from uterine cancer surgery. In 1999, he was disgraced again, having been caught in an affair with a 33-year-old congressional aide while spearheading the impeachment proceedings against President Clinton." Yet some quarters have anointed him the front-runner for the GOP nomination in 2012, and he certainly remains one of the most prominent Republicans in the snake-oil biz.

Sure, Republicans fire their immorality cases. Except for the ones they don't. Which is most of them.