Stop trying to put them in the shoes of the accused, and put them in YOUR shoes, the person whose life’ work has been attacked with a conversational rocket propelled grenade under the guise of cocktail party chatter.
Take hostages before trying to negotiate with terrorists. Turn table on your sanctimonious conversation partner by simply telling them that before you answer their question, which is a very good one, might they please tell you what THEY do for a living? Of course, they will be delighted, telling you with satisfaction that they have an honourable profession such as teacher or accountant or collateralized mortgage dealer, at which point you can parry with something like this:
“Oh, you are a teacher, wonderful. Tell me, how does everyone in your industry live with themselves graduating students who can’t read and write?” Or, “How is that you keep failing our minority students?”
As you watch their mouth open and close in astonishment, kindly tell them that you don’t really feel all teachers are bad, but thought they might like to know what it feels like to have their profession criticized so thoughtlessly. Then answer their question about your work. They’ll be so embarrassed they will listen and nod sympathetically.
You might not reform everyone of their rudeness, but it might make cocktail parties more interesting, and you will be practicing your lawyerly skills to boot.