In The Shadow of Robert E. Lee, explain: The South had a "more generous climate" which had led to a finer society based upon "veracity and honor in man, chastity and fidelity in women..."

This particular passage articulates the culture of Southern kindness and conformity to social codes of conduct. This showed that the South was not a backward society with an uncivilized population, as some in the North perceived the South to be.
However, these good qualities of the Antebellum South were more or less surface-level. Behind the kindness and politeness of the affluent class and middle class was the practice of slavery. The sophisticated social codes were in contrast to oppressive laws targeting African Americans, as well as limited rights and economic roles given to women.
While the Antebellum South was not a backward society in terms of presenting social graces and virtues such as chastity, its agrarian economy created opportunities for backward practices, such as slavery, to thrive. Behind the civilized manners of dressing, speaking, and interacting with other whites in the affluent class was a collective acceptance of human rights crimes.
In that regard, the passage generalizes all white Southerners and, perhaps, even affluent free blacks, as good in nature and righteous. The truth is there were many poor whites living in the South who did not have the education or social grooming of the affluent class.
Additionally, the particular excerpt portrays Southerners as a caricature rather than human beings. It is impossible for the quoted statement to be true, because all humans are prone to temptation, lust, infidelity, and promiscuity. The fact that some Southerners were immoral enough to own other human beings shows that those same Southerners were capable of acting upon other tendencies such as infidelity and lying.