I’ve lived in the South and can answer your question, at the risk of being flamed. This is the Bible belt, where a man can be forgiven for cheating on his wife, but never trusted to be alone with your own wife. According to the exit polls I saw, Santorum beat Newt among Evangelicals and the TEA Party, especially in Alabama.
What is wrong with the rest of the country could also be your question. He can hardly get out of the low teens anywhere else lately. So, I could very well be incorrect and it is something else that people do not like or do not trust about the man.
That reminds me of something a pastor told me many years ago during a time I was in Oklahoma. He said (and I am paraphrasing since it was almost a decade ago) that someone in the congregation can stand up during altar call, and go up and confess of how he used to use heroin/cocaine/meth. How he was a major alcoholic. Used to be a compulsive gambler and in the process lost his family and house. Or used to steal and rob. Or any number of things. The congregation will embrace him and use him as an example of the power of redemption. But dare he say he used to be an adulterer, or a woman say she used to be a prostitute. Basically, any sin seems acceptable apart from sexual sin, which will elicit a lot of 'looks' as if the person is anathema. Interestingly in the Bible Christ said something about throwing the first stone when a certain lady of certain 'repute' was about to be put to death. Also, I remember someone else saying at the church that, at many times (but obviously not all, or even most) that some of the people most vigorously shaking their fingers and tsk-tsking are also embroiled in the same sins.