Upton Sinclair intended to expose "the inferno of exploitation [of the typical American factory worker at the turn of the 20th Century]", but the reading public fixed on food safety as the novel's most pressing issue. Sinclair admitted his celebrity arose "not because the public cared anything about the workers, but simply because the public did not want to eat tubercular beef". Some critics have attributed this response to the characters, most of whom, including Rudkus, have unpleasant qualities. The last section, concerning a socialist rally Rudkus attended, was later disavowed by Sinclair. But his description of the meatpacking contamination captured readers' attention.
Sinclair's account of workers falling into rendering tanks and being ground along with animal parts into "Durham's Pure Leaf Lard" gripped the public. The poor working conditions, and exploitation of children and women along with men, were taken to expose the corruption in meat packing factories.
The British politician Winston Churchill praised the book in a review.