I believe the sanitary conditions and spoiled meat would have made the most impact on me as far as being disturbing.
"Jonas had told them how the meat that was taken out of pickle would often be found sour, and how they would rub it up with soda to take away the smell, and sell it to be eaten on free-lunch counters; also of all the miracles of chemistry which they performed, giving to any sort of meat, fresh or salted, whole or chopped, any color and any flavor and any odor they chose. In the pickling of hams they had an ingenious apparatus, by which they saved time and increased the capacity of the plant--a machine consisting of a hollow needle attached to a pump; by plunging this needle into the meat and working with his foot, a man could fill a ham with pickle in a few seconds."
"Also, after the hams had been smoked, there would be found some that had gone to the bad. Formerly these had been sold as "Number Three Grade," but later on some ingenious person had hit upon a new device, and now they would extract the bone, about which the bad part generally lay, and insert in the hole a white-hot iron. After this invention there was no longer Number One, Two, and Three Grade--there was only Number One Grade. The packers were always originating such schemes--they had what they called "boneless hams," which were all the odds and ends of pork stuffed into casings; and "California hams," which were the shoulders, with big knuckle joints, and nearly all the meat cut out; and fancy "skinned hams," which were made of the oldest hogs, whose skins were so heavy and coarse that no one would buy them--that is, until they had been cooked and chopped fine and labeled "head cheese."