I have a cat that lives with my parents, and the first thing I do when I visit is clean is eyes and nose boogers. I sits so still.
2 years ago he also had an issue in his ears, so I had to clean them every day. He wasn’t fond of it, but after a few days he got used to it and would just stand still and wait.
I’m sure that if they could talk, they would say the same about us. “I lightly bite my human for play. At first they would get scared but now they are so trusting, it’s like they now”.
dogs are smart and Crazy emotionally intelligent, i cant say she understands what your doing for sure, but she does stay still for you because she understands that its a sign of love and care.