If robots end up becoming sentient and are not biological they won’t have evolved like we have being vulnerable to bacteria, diseases and poisons/toxins and because of it our sense of smell detects bad odors, we wash our hands, take showers and have a strong aversion to things that disgust us.
Robots may just happily pick up shit, dive in dumpsters and roll around in sewage. And why wash your hands or take a shower when water could hurt you? Who even knows if they would perceive smell the same way we do.
Perhaps, or a freshly cleaned and lubed engine at normal operating temperature.
Hell, they might not smell like anything at all. There’s a company that is making artificial muscles for robots that only involve water, pressure, and tubing. I think the rest of the bot is plastic.
https://interestingengineering.com/innovation/humanoid-torso-clone-water-powered