I take it in the spirit it was intended. If someone is trying to be funny, or laughing at Thor, I will usually chuckle along with, because Thor is a funny little dog. He makes me laugh all the time and I love that about him. I think calling dogs rats is rude, and usually the person is saying "I don't like small dogs". Too bad for them, they are missing out.
I will also say that sometimes Thor decides to bark his fool head off at a stranger, and I am always greatful when they joke about him being a guard dog and such, rather than sneering at my poor dog handling skills.
On the flip side, I do find myself exclaiming over big dogs that they look like moose, horses, bears, etc. Their owners are probably pretty tired of those jokes too.
