In Chapter 5 of Huckleberry Finn by, Mark Twain, Huck's father is described as follows:
He was most fifty, and he looked it. His hair was long and tangled and greasy, and hung down, and you could see his eyes shining through like he was behind vines. It was all black, no gray; so was his long, mixed-up whiskers. There warn't no color in his face, where his face showed; it was white; not like another man's white, but a white to make a body sick, a white to make a body's flesh crawl—a tree-toad white, a fish-belly white.
This first physical description is indicative of a sick man. However, the most important element about the way that Huck describes his father is that, prior to the description, he says the words
I used to be scared of him all the time.
The looks of a parent may bring some disdain in a child, but what Huck felt was terror of him. This, combined with the father's physical description leads the reader to realize that Huck has been victimized by his father's alcohol addiction and lack of self-control.
The reader also gets the feeling that Huck sees his father from a different perspective now that he has been away from him. Moreover, Huck is slowly maturing throughout the novel. His observations are now more analytical, and we even detect a hint of embarrassment when he describes his father's clothes.
As for his clothes—just rags, that was all. He had one ankle resting on t'other knee; the boot on that foot was busted, and two of his toes stuck through, and he worked them now and then. His hat was laying on the floor—an old black slouch with the top caved in, like a lid.
This being said, we can safely argue that Huck's father shows the signs of advanced alcoholism not only in his behavior, but also in his physique, and in his personal upkeep. He is careless, raggedy, mean, and irresponsible. Moreover, he is a bad parent who cares very little about what his son thinks of him. The physical description goes very well with the man's horrible way of life.