The reason some words are uncomfortable to her is that she associates them with unpleasant emotions. Pavlov's dogs; dinner bell rings - dogs drool. That stuff is completely individual; you may not think much of the word "cunt" but someone who has been called "cunt" repeatedly while arguing, or having done something stupid or generally in some form of emotional distress will associate the word with feeling bad, rejected, worthless.

You can change that association by using the word when she's feeling good; the closer to orgasm the better. You can soften the impact of it by not directing it at her. For example, you could say "Oh, I love sluts" instead of "You're such a slut"

Anyway, consider the fact that individual words have emotional meanings to her that you (or even she herself) are not necessarily aware of. Simply avoiding what makes her feel bad might be easiest.