Fun fact: rats can’t vomit.

That's one of the reasons humans and dogs created such a good symbiotic relationship. They would eat things, like waste and refuse, that if left around would make humans sick. They got an easy meal and we got protection from food borne illness and rodents.

I remember reading an article once about how difficult it is to make dog food. Because they have to make it appealing to dogs while at the same time not making it so gross that humans would be turned off at the site and smell of it.