re: learning how to pronounce foreign words via exaggeration—a friend told me that pronouncing Japanese words in the most racist way possible actually earned him nods from his teacher.
When I was taking Chinese classes, our teacher would always demand that talk loud, exaggerate the pronunciation, and be as over-the-top as possible. Apparently there's a popular english learning method in China called Crazy English that takes this approach.
Mockery such as making fun of someone's accent surely does not constitute racism. If racism can be anything, then it loses its meaning.
That exaggerated accent came from somewhere. It wasn't just invented by racist people for fun, though I'm sure it's changed over time.
Teaching my wife her Katakana has been fun, all the words on the flash cards are loan-words, mostly from English, and the correct readings of the words certainly give her pause.