I'm not sure, because rats seemed to like him always, but there's no rat smell detectable to humans most of the time. Then again, looking up what a clean rat smells like (rather than their droppings), apparently the males smell like tortillas, so maybe he does, but since he bathes, wouldn't really smell bad. Scott can probably pick up on at least a bit of rattiness all the time, though, but a whole lot more when he shifts.