Sedit, I don't give a shit what people say about me personally, on the most part, well, if someone is cheeky enough I might well give them a good beating (not saying that about you personally, just about idiots in general who get uppity and thinking its clever to gob off at me) but its offensive in the extreme, and more to the point, to see it used as an insult to morons (its true that moron, idiot, and cretin were once used as medical diagnoses for those with mental retardation, but that was over a century ago, and they have long, long since lost their meaning in that sense, indeed the term 'cretin' was quite probably originally a term meant kindly towards those with MR, from the french "chr'etienne" meaning 'still christian', I.E 'still a human being worthy of the same kindness and respect afforded others')
Why? because it subtly encourages people to hold those with MR in contempt, as less worthy of respect, and as lesser human beings, call somebody a 'fucking retard' for instance, who does indeed, deserve insulting, it isn't just heaping the most justifiable ordure on THEIR heads, but also on the heads of those with MR, who are the source of the insult. The point being, that it shouldn't BE an insult at all, most people who are MR are good people, its rare to see deliberate cruelty, hypocrisy, backstabbing perpetrated by MR people, but just look how much of that you see dripping from NTs.
Indeed, I have dated a few mentally retarded girls, and they have without exception, been very loving, and straight up in my dealings with them. I find I connect with them better emotionally, and feel more kinship with them, than I do any NTs.
'spastic' or 'spacker' are just as bad, worse in fact. And none of those terms should be used as an insult against the deserving, there are plenty of other epithets and curses available to put your average piece of bipedal, mammalian diseased canine ordure down a peg or three, without having to lower yourself to taking the piss out of genuinely mentally retarded people.