One of my friends is doing some toilet research and showed me an excerpt he found, which describes how an engineer tests toilets at a particular company :

Every manufacturer tests toilets coming off the line. However, many manufacturers have created their own tests in addition to the ASME/ANSI requirements. One company that has its own set of standards is Toto, the world's largest plumbing-products manufacturer. At the Toto toilet factory in Morrow, Georgia, an engineer tests toilets in a remarkably real way. He doesn't actually defecate in them, but it's close. Using a proprietary ingredient that closely resembles human feces, the engineer measures out up to 400g of this faux waste and then molds it into its familiar tubular shape.

After plopping the artificial waste into the toilet, the engineer wads up toilet-paper balls and drops them in on top of the bogus poop. Standing there in the factory watching him do this, I felt like asking if he wanted to be left alone. The purpose of this realism is to ensure that the toilets meet or exceed ASME flush standards.

Imagine this guy telling people what he does for a living : "I make fake poop, then put it in a toilet with wads of toilet paper, to test toilets." I reckon somebody has to do it… but I wouldn't want to put it on my resume…