In A Christmas Carol, Dickens uses different places and environments to build a strong sense of character. In the first chapter, for example, Scrooge's house reflects many aspects of his character: the rooms are "old" and "dreary," the hallway is dark and we learn that Scrooge is the only resident of the entire building. This lonely place complements Scrooge's character well, then, because it represents his desire to be separated from other people, his icy temperament and his miserliness.
Similarly, in chapter four, the descriptions of Old Joe's Shop are very similar to and contribute to our understanding of Old Joe. Situated in a neighbourhood which reeks of "crime, filth and misery," the shop is surrounded by cesspools, "wretched houses" and people of ill-repute. These characteristics put the reader in mind of Old Joe himself: a petty criminal who makes a living by selling stolen goods and seems content to live among mess and dirt.
So, while these characteristics may be highly-exaggerated (an area can't smell of crime, for example), they go a long way in creating a strong impression of a particular place or character in A Christmas Carol.