Quick dirty answer: It's almost impossible to sort them out. That - of course - is why it's so crazy. Compound it with the set who like to use words normally considered bigoted vulgarities on and to each other ('nigger', anyone?).

Confusion is the rule.

And - since we're near to the topic - let's not get into when I try to actually (gasp) use the word 'niggardly'. It's as good as my rhetorical life when I do, sometimes even when I'm writing in a sympathetic forum. >rolleyes< Stupid, stupid, stupid ... I HATE it when MY language must be stilted by the biases and ignorances of fools - and that is every single day.

Somehow, I think you know what I mean.