Earlier quoted context omitted.
They wash their hands. What's so gross about them going extra lengths to cleanse themselves? Its not like they're going to then ignore their very hands, considering for many, its a religious law to be clean. It seems like bidet fear but 10x. For no good reason.
Have you ever got poop on your hands? That smell does not go away with just soap and water.
The reason poop stank is so persistent is because human feces passes large quantities of oils and fats, which are the really messy aspect of poop. The stench is embedded in the non-evaporative oils and grease, and comingles with the oils from the sebacious glands of your skin. To cut through that stink, you need to chemically strip the oils that retain the aromatic grossness.
Dish soap works too, but it really isn't designed to be skin friendly or have cosmetic appeal. Dish soap is stronger, and you don't need as much, which makes sense. Dish soap is intended to destroy food baked onto pots and pans, which is tougher than what your gastric juices do to food.
Shampoo isn't as strong as dish soap, but the right kind will destroy any odor, and it's easier on your skin than dish soap.