How does Twain satire the cultural affectations of the American South in The Adventures of Huckleberry Finn?
I think this is a reference to the extent of which the Grangerfords decorate their home, similar to the Victorian customs found in England during this time period.
The Victorian style of building, furnishing, and accessorizing a home could be described as favoring the "ornate, rich, and expensive." Victorian decor favored large pieces of furniture, lavish use of fabric, decorative objects on all level surfaces, lots of books and lots of artwork on the walls.
Upon having time and opportunity to investigate the Grangerford mansion, Huck discovers it to be an unusually fine example of a Victorian home for its location in the country. "I hadn't seen no house out in the country before that was so nice and had so much style." Twain allows Huck to describe what he observes as he explores the mansion. In doing so, Twain is laughing at the types of objects that were considered as fashionable for display in the home of a refined and well-to-do Southern family.
The mantel over the fireplace in the parlor held a wind-up chiming clock, "a big outlandish parrot on each side of the clock, made out of something like chalk, and painted up gaudy," a porcelain cat and a porcelain dog, and "a couple of big wild-turkey-wing fans spread out behind those things." A table in the room's center featured books in perfectly aligned piles (implying that they were never disturbed or read) and a basket containing artificial fruit that
was much redder and yellower and prettier than real ones is, but they warn't real because you could see where pieces had got chipped off and showed the white chalk or whatever it was, underneath.
Twain allows Huck to spend most of chapter 17 describing every ridiculous and overly done flamboyant feature of the parlor in great detail. Twain's disgust with the style is expressed when the decorations include things like crayon drawings that were far from what Twain would have considered as having "so much style."