I've heard a lot of horror stories about Amazon warehouses. I'm sure a lot of it is FUD or whatever, but it seems that even Walmart has better conditions.
Another fun job was to re-palletize boxes. A forklift operator would lay an empty pallet on the ground, then put a row of 25 full pallets next to it in a long row. You had to unstack the 2nd pallet onto the empty one using a new stacking pattern that was more stable. Then the 2nd pallet would be empty. Repeat the process down the row as fast as you can go getting cuts on your hands from the cardboard boxes, leaning over your back lifting heavy boxes without AC in a hot warehouse.
I would like for those kind of jobs are staffed by a staffing company so people can cycle through them rather than having to do it full time. I can put up with a lot for a few weeks at a time.