Yet some of the results are not exactly what one might expect. Mississippi, with a household income in the low $40,000s, has a higher median credit score on Mortgage Marvel’s list than the national average of 684.

Rick Allen, COO of Mortgage Marvel, cautions that there’s a story underlying the data that might not be obvious to the naked eye.

“There’s a little bit of self-selection going on here,” said Allen. “The people with not-as-good scores don’t apply, because they think without stellar credit they won’t qualify.”

Indeed, while income is a good indicator of where credit scores will end up, the price of real-estate seems to determine who applies, and how good their credit is.

This is especially true of places at the upper end of Mortgage Marvel’s list. While Maryland regularly ranks as the top state for personal income, the state doesn’t make the top ten in the best credit scores for mortgage applicants. That is because Maryland ranks out of the top third for states with the highest average listing price, according to Trulia.com.

California and Hawaii are both ranked among the top four states for average home price.

(Read more: Renting Beats Owning, But Both Take a Bigger Slice)

Those applicants with scores in the mid-700s, said Allen, “are people who can afford a $500,000 home.”

At the bottom of list, income is more of a determinant. In the middle, each one seems to have its story to tell.

South Dakota, number 36 on Trulia’s list for average listing price, ranks at 24 for average credit score. The result, as Allen pointed out, is due to incomes inflated by the upper Midwest energy boom.