Bingowings said:

Watching Buffy The Vampire Slayer used to be a bit problematic in Britain because Americans don't use the term "Spastic" or "Spaz" in the same way it has been used here.

"Spaz" in Britain is a term used to target people suffering with Cerebral Palsy and "Spastic" by the mid-seventies had become so commonly used as a derogatory term that the National Spastic Society eventually felt it necessary to change it's name to SCOPE.

I am not sure what gave you the impression that the term is used differently in the States, but as an American, I can confirm that "spastic" and "spaz", for short, both refer to CP here as well.

When I was a kid to call someone a spaz was to suggest that they were uncoordinated or incompetent physically and/or socially. A guy who loses control of his tongue when talking to a pretty girl, or someone who totally fumbles the ball when it was thrown to them in football, both would have been accused of being spazes when I was in school (and Buffy was airing). "Retarded" and "gay" were common insults (though also frequently used among friends) back then as all, and all three have kind of fallen out of use in today's much more politically correct world.

Jawas seem to be a fully sentient species with a culture and a language so is Threepio being racist when he calls them "Disgusting creatures"?

I think he is.

Whoa, wait? Where is your history of repression here? There are no indications in the film that Jawas are repressed. We see them drinking at the bar and all over Mos Eisley like any other kind of alien, and in fact, we probably see more of them than any other one type of alien (including humans), so it is even possible they could be the majority or the planet's native inhabitants.