It's definitely between Don, Ryoshu, and Rodya. Don definitely doesn't clean herself, and given how long she's been alive that's a Lot of smell build up. Ryoshu, on the other hand, likely actually tries to accumulate as much stench build up as possible, such as wearing tight pants that hold in her sweat better. Rodya is completely unlike the other two, though. She actually cares about hygiene, but has been "gifted" with a unique proficiency for smelling bad. She always leaves the shower only smelling worse than when she entered it, and given the immense size of her ass, scrubbing it usually just moves all the nastiness deeper within rather than taking it out.