First, there are inversions that take place in ideology. The dominant see the cause of oppression in the subordinated (instead in themselves, much less in the structure of oppression). In _The Great Gatsby_, Fitzgerald makes Nick Carraway observe: "Wilson was so sick that he looked guilty, unforgivably guilty -- as if he had just got some poor girl with child." Wilson is one of the novel's few poor characters; and Nick's friend Tom Buchanan -- a rich racist snob -- has been having an affair with Wilson's wife Myrtle, and Tom in part derives his enjoyment from the fact that his affair confirms (in Tom's eyes) Wilson's weakness. Nick knows this, but he still makes the above comment about Wilson's guilt when comparing Tom's health and vitality with Wilson's weakness (in all important respects that matter in a sexist class society). The rich resent the poor for being poor and making a nuisance of themselves. Some whites may resent blacks for the same reason. Oppression often causes degradation, and degradation is ugly, aesthetically unpleasing, or so think the comfortable (such as Nick and the implied reader of _The Great Gatsby_). Further, degradation, due to our fondness for the disease metaphor to describe it, may look even contagious, which is in part materially underpinned by the fact that poverty forces the poor to live with filth and public health problems. Significantly, in the novel, the poor Wilsons live in the "valley of ashes" -- an industrial waste land of pollution: "This is a valley of ashes -- a fantastic farm where ashes grow like wheat into ridges and hills and grotesque gardens, where ashes take the forms of houses and chimneys and rising smoke and finally, with a transcendent effort, of men who move dimly and already crumbling through the powdery air. Occasionally a line of grey cars crawls along an invisible track, gives out a ghastly creak and comes to rest, and immediately the ash-grey men swarm up with leaden spades and stir up an impenetrable cloud which screens their obscure operations from your sight."
Images of the holocaust -- the pictures of Jews being physically degraded and reduced to nothing -- make the anti-Semites think in a similar manner: Jews were degraded, and they were responsible for thus making a nuisance of themselves.
Then, the dominant feel doubly outraged when they see the subordinated (in their eyes, preposterously) making a claim upon the principles of justice and mutual respect, which have historically (until the rise of capitalism & the bourgeois revolution) been based upon the premise of the meeting of equals. For instance, Thucydides, in the Melian Debate, has Athenians say to Melians: "We both know that decisions about justice are made in human discussions only when both sides are under equal compulsion; but when one side is stronger, it gets as much as it can, and the weak must accept that." Nietzsche saw ressentiment in "the weak trying to bring down the strong," for instance, through Christianity (which he thought of as a levelling ideology). He got it ass backwards. More likely, it is the dominant who feel resentment for having to allow the subordinated to claim "justice & mutual respect." Why do the dominant have to allow this "monstrosity" in their eyes? Because of the ideology of equality. However, this ideology of equality is belied everyday by the material workings of capitalism reproducing inequality. This triangular relation -- the older idea of justice & mutual respect based upon the principles of equal strength, the bourgeois ideology of class- & race-blind equality that legitimates capitalism, and the material inequality that contradict both of the above -- must in some way explain why some whites feel that they are "unable to forgive blacks for allowing whites to oppress them."
Yoshie