Are rats dirtier than cats?

Whether rats are dirtier than cats depends on whether you mean wild rats or pet fancy rats, and what type of dirt you are talking about. Wild Norway rats and roof rats are definitely dirtier than pet cats, because wild rats live in sewers, garbage areas, and inside walls, come into contact with sewage and decaying material, constantly urinate to mark territory, produce many droppings that contaminate food and surfaces, and can carry pathogens like salmonella, leptospirosis, and parasites like fleas and mites that can spread to humans. Their gnawing and nesting also cause property damage and odor. Pet cats, on the other hand, are generally very clean animals that groom themselves extensively, bury their waste in litter boxes, and are bathed and vaccinated, though they do shed hair and track litter. Pet fancy rats, however, are also extremely clean, they spend hours each day grooming themselves and each other much like cats do, they can be litter trained, and they do not have the same disease risks as wild rats when kept in clean cages with weekly cleaning. In terms of personal grooming, pet rats are comparable to cats and may even groom more frequently. So wild rats are much dirtier than cats, but domesticated pet rats kept as companions are quite clean and can be as clean as or sometimes cleaner than cats in terms of grooming habits, though both need regular care.