I've always thought "douche" fairly mild and am surprised to hear you think it so offensive, Forrest. Do you suppose it's an unconscious reaction to the fact that the douche is used for the cleansing of ladies' nether regions? If so, I call (unintentional) sexism.
As for "cunt," I used to hate it and still dislike it when Americans use it, because they tend to do so truly hatefully. But Brits use it so casually, it takes on an entirely different aura, and the Canadian (possibly only Campobellan, for all I know) "cunthead," used for men and women, always makes me laugh. Besides, "cunt" is a fine Anglo-Saxon word; I wish it could be rehabilitated in the US of A.