Anyway, Mao became convinced that the place was bugged, and took to shouting at the walls that he was there "to do more than eat and shit." Which we know, because obviously the place was bugged.
But it's the shitting part the Soviets were truly interested in. According to former Soviet agent Igor Atamanenko, the Russians had secretly disconnected all the sewage lines in the house and rerouted the pipes to special boxes, which collected Mao's bodily waste each night. Stalin himself ordered secret police chief Lavrenti Beria to steal his rival's precious poop, in what was surely the stupidest espionage plot hatched this side of a Tom Clancy novel.
According to Atamanenko, the Soviets were trying to put together a psychological profile of Mao, and thought stool analysis could help with that. For example, if their tests found an excess of the amino acid Tryptophan, they might conclude that Mao was a pretty chill dude. But not enough potassium would mean he was a real nervous nelly, and probably not down to party. Sadly, we do not know what results they came up with, but in a bit of happy news for Mao, he eventually got his revenge on the Soviets. He forced Nikita Khrushchev to don water wings and nervously doggy-paddle around in a swimming pool, all while Mao swam laps around him.