One book I've heard about a million times in history courses is Upton Sinclair's The Jungle. The things you remember is that: it's about the beef-packing industry and that Sinclair aimed for America's heart but hit it in the stomach. Maybe you also learn that Sinclair was more concerned with workers' rights.
After reading this book over my winter break, I can't see how everyone missed his point. Basically, the book follows a Lithuanian immigrant named Jurgis and his family. They end up in Packingtown, Chicago and suffer numerous mistreatments at the hands of capitalists. There are graphic depictions of the level of poverty and suffering of this family, which is supposed to be taken as a case study, reflecting conditions of all families living in the area. Basically everyone works until they cannot anymore, all the while suffering unthinkable abuse from their employers and anyone else who is not in the lower class. Without adequate funds, many go hungry or turn to prostitution or live in a space smaller than a jail cell.
There are only about 10 mentions of the gross things that packinghouses do to the food and I believe that they were included to show that the capitalists had no regard for anyone's wellbeing; they were not exclusive to not caring about their workers. Sinclair sets up the profit motive as sinister. I will concede that human rights should not be violated in the quest for profit. I imagine that the reason the free market failed to protect consumers from rotten food and workers from abuse is a combination of politics and an information problem. Consumer watchdog groups can help bridge the information gap between the public and what goes on in the stockyards. As long as politicians need campaign money, I don't think it is possible to fix the graft problem.
Some also say that Sinclair was expressing his socialist agenda. The only time I saw this in the book was near the end when Jurgis finds out about the socialist party, BUT all portrayals of the socialist party make it sound far from ideal. I guess I can't ridicule his contemporary readers for missing the mistreatment thing when I missed the "socialism is good" thing.