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.
Clean machinery last longer.
Bingo. I think they’ll just smell like warm oily metal, but otherwise will clean themselves.
Cars are machines, they get wet and have protections around the parts that shouldn’t get wet. Why would robots be less complex?
So they’d smell like a freshly oiled gun? Not sexy, but I could deal with that.