Who would be polite to a costumer of Dilbert's company? I'd say it's quite hard to avoid NOT being impolite to such a person who, obviously, can't think normally.
It's a bit unusual for Dilbert to be so impolite, but the fact that she is a customer... It affects the way you talk to the person in question.
Awesome! Germophobia is the popular thing these days, but I think it's counterproductive...the immune system needs some practice after all. I know a guy here at the hospital who eats his lunch off of the lid of a dirty needles container. That dude's going to live forever...