How does Chaucer satirize the middle class? Does he have a specific complaint about them?

All those people working would be considered members of the middle class. They are working because after the Black Plague, there were not as many serfs to be considered as slaves on the estates of the nobles. Each worker has an interesting "quirk," but the Oxford cleric, for example, is so thin because he spends all his money on books and learning. The Miller is a drunk who cheats people in the work he does, and he looks bad with the wart on his nose with hair growing out of it. Chaucer makes each character very distinctive.