It's been an awfully long time since I've used any of the disparaging words in this public service announcement. Except for retarded and retard. I'll admit it. And in the internet age, we've co-opted it (lib-tard, celebutard, etc.). I think it's proably because the "r" word came into common usage in my growing up years. We even had a room called "EMR" which was education for the mentally retarded. There were no sensitivity organizations, or empowerment movents around the issue. And it was rare indeed for any of us kids to actually make fun of the actually mentally retarded.
No, the "r" word was reserved for the willfully stupid, or the insufferably dense. Does that make it okay to use, that we weren't directing it at people with mental disabilities? No, I suppose it doesn't. It's similar to kids using "gay" when they mean stupid. I mean really similar. Except that today's kids are aware of the double meaning, and typically use it as an all-purpose smear. All in all, I will cop to having used the "r" word, and I will endeavor to stop doing it. And one day, it'll join the list of things we don't hurl at each other without feeling really bad about it.