Plant urban legends

In the comments at In the Pipeline (about a sad story of a Boston-area biotech where a single lab scientist was cooking the results for important assays), this story (which the commenter notes is apocryphal): 

I took an industrial job out of grad school. An old-timer told me about a plant where the foreman of the night shift got better yields than anyone else. Nobody understood why. So they hired a private eye to work as a janitor and keep an eye on what the foreman was doing. Turned out he was peeing into the reactor.

I have heard much this same story, but it was that the operator or the janitor was spitting their chewing tobacco into the reactor...