Entertain this notion; words mean things, whether you like it or not. Your conscious state of mind is completely irrelevant to anyone but yourself. When people roll their eyes at your unfunny racist jokes, it's not necessarily because they think you're racist; it's because you're saying racist things.
So, why is it offensive to say black people are criminals who love KFC and watermelons? Well, maybe you should ask a black person, because you certainly wouldn't know. But be sure to use "offensive" in scare-quotes to hammer home the point that you Just-Don't-Get-What-The-Fuss-Is-All-About. Remember also to point out that most people are too stupid/crazy to understand why AIDS jokes which may include a synonym of the word "faggot", can be offensive to homosexuals. Because hey, it's just a word after all. There couldn't possibly be any societal, cultural, or historical contexts behind words, right?
And then you blab on about sexual taboos like it has any real bearing on anything. But really what could anyone expect from someone who thinks that the attempt to use more inclusive language in public discourse amounts to "the ultimate kind of bigotry of them all".
Crap like that runs rampant on Reddit.
When someone complains about "political correctness", the first thing I do is figure out if "LA LA LA LA LA LA I CAN'T HEAR YOU" would be a good substitution.
It's not a universal replacement, but it works a surprising amount of the time.