Twain is satirizing Huck's evaluation of the Grangerford house as being "a mighty nice house, too. I hadn't seen no house out in the country before that was so nice and had so much style."
The Adventures of Huckleberry Finn is set in the pre-Civil War years, a period of time when a widely adopted style of construction and furnishing of homes was called the Victorian style in honor of England's Queen Victoria, who reigned 1837-1901. "The Victorian era is...widely viewed as having indulged in a regrettable excess of ornament." The Grangerfords, as wealthy landowners, could afford the best that was available when they built and furnished their home, so it is very Victorian in construction and furnishings.
When Huck describes in great detail the hardware, the fixtures, the furniture, the decorations, the wall hangings, and many other features of the Grangerford's mansion, Twain is making fun of the over-done ornamentation and decoration of every available space. Twain is also making fun of Huck's evaluation of the Grangerford home as being "mighty nice" - Twain didn't appreciate the pretensions of the well-to-do.
In Chapter Seventeen of Mark Twain's The Adventures of Huckleberry Finn, Huck, the story's narrator, is introduced into the world of aristocratic excess in the persons of the Grangerfords, led by family patriarch Col. Grangerford. Huck, of course, comes from simple means, and has resisted any efforts on the part of others to educate him so that he too might grow up to a man of wealth and comfort. He has run away from home, teamed up with the escaped slave Jim, and gone on the adventure of his life, traversing the Mississippi River on his raft while encountering all matter of humanity and escaping from dangerous situations. It is at the Grangerford home, however, that he sees for the first time true wealth, and the superficial emotionally-empty trappings of that wealth.
Twain/Huck take pains to emphasize the upper-class nature of the Grangerford family, despite its old world feud with the Shepherdsons, another wealthy family, that has cost the Grangerfords dearly in blood and money. In describing the colonel, Huck notes that "Col. Grangerford was a gentleman, you see. . .He carried a mahogany cane with a silver head to it," and ". . .owned a lot of farms and over a hundred niggers."
Point made: The Grangerfields represent the elite of this society. They are educated, civilized, refined and proper, and they have a house that mirrors the ostentatious nature of the aristocracy in Twain's world. Twain devotes considerable space to his/Huck's description of the Grangerford home:
"I hadn’t seen no house out in the country before that was so nice and had so much style. It didn’t have an iron latch on the front door, nor a wooden one with a buckskin string, but a brass knob to turn, the same as houses in town. . .There was a big fire-place that was bricked on the bottom, and the bricks was kept clean and red by pouring water on them and scrubbing them with another brick; sometimes they wash them over with red water-paint that they call Spanish-brown, same as they do in town. . .There was a clock on the middle of the mantel-piece, with a picture of a town painted on the bottom half of the glass front, and a round place in the middle of it for the sun, and you could see the pendulum swinging behind it."
Twain/Huck's description of the Grangerford home continues for some length, with descriptions of wall-hangings, crockery shaped like house pets, books ostentatiously displayed, and so on. The point of all of this description? Twain was commenting on what we today call "conspicuous consumption," the spending of large amounts of money on expensive material goods the practical value of which is limited and the consequence of which purchases is to convert a home into a sterile museum devoid of warmth. Twain is reminding the reader that the aristocracy may have more money, and more items, but they may be purchasing expensive items as a replacement for a wounded or missing soul. Accumulations of expensive trinkets cannot compensate for the deaths of family members to the senseless feud with the Shepardsons, or for the loss of the family poet, Emmeline.
By focusing on the Grangerford family and home, Twain is illuminating the spiritual emptiness inherent in a clan that has, somewhere along the way, lost its way.