It is most irritating to be sure. I get the same comments when I tell people we have ferrets. And you should see the reaction when they discover we have 2 snakes. Sometimes it is quite funny. Perhaps, rather than being offended you should take the time to educate the people on how wonderful it is to have a rat as a pet.
omg i have the same problem with telling people about my snake there like oh dont they bite you, im like ummm nooo..they are socialized, dose a dog bite you if it lives inside with people..noooo
and then when im out with my bunny WOW people can be retarted they always say oh poor thing is probly frightened to death...(ya cuz ya know she hasnt been coming out shopping with me scince she was 3 months ) or they say is that a wild rabbit cuz of her markings..ya id really be able to carry a wild rabbit around.. omg i hate people sometimes