Not really sure how to search this, though I took a vague stab at "slang terms (1940s OR ww2 OR "world war 2")--can't tell levels of rudeness very well, however, and there wasn't much on relatively generic nasty names.
Our Heroine is from a wealthy family (and fairly proper/correct/prim), but she's a bastard (in the literal sense, basically no one but her mother knew who her father even was). So I don't think she'd use that as a pejorative term (if, for example, she ever meets her absentee father and wants to call him something rude)--it would be too sensitive of a subject for her.
But I have no idea what other words a relatively gently reared 25-year-old would *use* in the early '40s to indicate that someone was worthless/bad/morally corrupt/etc, or otherwise indicate extreme displeasure. Having her call someone a f***-head or a**hole or whatever just doesn't feel right at all--I don't think someone of her class and upbringing would speak like that.
(She's a surgeon, and also knows French and Latin, if that suggests anything in particular to anyone)