Many people believe that a dog's mouth is cleaner than a human's mouth, but scientific evidence suggests otherwise. While dogs have certain enzymes in their saliva that help kill bacteria, they also engage in behaviors that expose them to a variety of germs and parasites. Dogs lick their own bodies, eat feces, and investigate unsanitary objects with their mouths. This can introduce harmful pathogens into their mouths, making them potentially dirtier than a human's mouth. In contrast, humans have better oral hygiene practices such as brushing and flossing regularly, which helps keep their mouths cleaner. Additionally, humans are less likely to engage in behaviors that expose them to harmful bacteria and parasites. Ultimately, both species can have bacteria in their mouths, but it is important for dog owners to be mindful of their pet's oral health and hygiene.