Discussions of PC most often center about race, which is a distraction from both race and PC-ness.
If I see someone in a wheelchair I say they are crippled. Right away someone says, no-no, they are "handicapped", but another jumps in, they're "motion restricted". Whoa stop, they are "locomotion attenuated". By the time everybody settles on an acceptable terminology, everyone is butt hurt and it's way passed bed time. Meanwhile nothing of value has been discussed, and whenever I hear any of those terms I automatically translate to cripple in my head.
If you are bored, and want to kill a lot of time while making a lot of enemies, describe someone retarded.
Recently in an automotive forum, a guy was describing an ignition timing problem, saying it was acting retarded. Right away two people jumped on his shit for using that word. Mindless reaction, no brain involved... retards.