One thing I've done to help with the smell is put a smaller air purifier on low next to it running continuously. This really helps a lot in my experience compar

One thing I've done to help with the smell is put a smaller air purifier on low next to it running continuously. This really helps a lot in my experience compared to having nothing. It can still smell a bit if the robot is full and nothing is cycling or one of the cats has just used it, but other than that there is largely no smell. The other thing that helps a lot is changing the carbon filter on the robot on a regular basis, maybe every couple or few months, since once that goes a lot more smell leaks out.