Its a Brand.

Tom at 538 interviews the head of the Repub Governor's Association:

538: Turning to Mark Sanford, he joins a growing list of socially-conservative Republicans who look hypocritical because of their own marital infidelities. How much damage do episodes like Sanford’s inflict on the Republican brand, and specifically the Republican boasts about being the so-called “family values” party?

NA: What Mark said in all the years I’ve known him, is that the party is exactly that—it’s a brand. It’s no different than John Deere or Caterpillar or Chik-fil-A. Those are the three examples he would give. He would go on to say that when people were buying those brands they knew what they were getting, and they knew it was worth paying the price for the quality they got in return.

What NA didn't mention is those brands are brands because the companies behind them produce products that work as advertised and add value or in Chick-fil-A's case have cows.