How we cite our quotes:
What, what, ye sanguine, shallow-hearted boys!
Ye white-limed walls! ye alehouse painted signs!
Coal-black is better than another hue,
In that it scorns to bear another hue. (4.2.15)
Aaron declares those with "coal-black" skin are "better" than those with white skin because black "scorns to bear another hue." In other words, Aaron is saying that a black woman will never give birth to a white baby.
I blush to think upon this ignomy. (4.2.12)
Both the Romans and the Goths are disgusted by the product of Aaron and Tamora's interracial coupling. What's bizarre about this passage is how Chiron (a rapist and murderer) says he's embarrassed by his black half-brother.
Why, there's the privilege your beauty bears:
Fie, treacherous hue, that will betray with blushing
The close enacts and counsels of the heart! (4.2.12)
When Chiron claims to be so embarrassed by his mother's affair with a black man that he can't help but "blush" (see above), Aaron mocks him for his presumption that white skin is superior to the black skin of his new half-brother.