If I didn't know better, I'd suspect the authors of being Yankee carpetbaggers bent on exploiting the goodwill enjoyed by southern girls and southern culture, because I'm not convinced these ladies get it.
As a daughter of the deep, deep south, I hope I can set a few things straight.
1) "Y'all" is always plural. "Y'all" used in reference to one person is the mark of a bad screenwriter and a bad mimic, neither of whom has ever ventured below the Mason-Dixon line. Sometimes you may hear someone say to another, "I hope y'all can make it to the party," or "How are y'all enjoying the new lake house?" in which case it means "you and yours (not present)." If a lone Southern neighbor drops by for a visit on a Sunday afternoon, don't say, "Y'all come on in" unless you want your neighbor to suspect you're already in your cups and seeing double.
2) The expression is "A whistling woman and a crowing hen never come to a good end." This book records it as "A whistling woman and a crowing him...." As if that means anything at all.
3) "it's" = "it + is" while "its" = "that which belongs to it"
If these "GRITS" don't know the difference or can't find an editor who does, they should get in touch with me. I know several, in Alabama, no less. The authors aren't perpetuating the myth of southern charm; they're perpetuating the myth of southern ignorance.
Truly, if you want the mysteries of southern charm revealed, stick to King's Southern Ladies and Gentlemen or Rich's What Southern Women Know.