Why were strangers given tours of Durham? How did the visitors take the tour?

The tours are advertisements for the companies and the multiple products that they sell: “Durham’s Pure Leaf Lard...Durham’s Breakfast Bacon, Durham’s Canned Beef, Potted Ham, Devilled Chicken, Peerless Fertilizer!” The people are sickened by what they see. Some cannot help but become philosophical about the process and think on the idea of an afterlife for hogs, and on how each hog “had an individuality of his own, a will of his own, a hope, and a heart’s desire.”