One thing that has been bothering me...
Re-tarded(ed) is not a slur (even though Bork thinks it is).
verb (used with object)
to make slow; delay the development or progress of (an action, process, etc.); hinder or impede.
verb (used without object)
to be delayed.
noun
a slowing down, diminution, or hindrance, as in a machine.
Saying "you are a re-tard" is an insult. Saying "you are re-tarded" is an insult.
But "the train is re-tarded" is not an insult or slur.
Neither is "the burning of the Alexandria library re-tarded progress for centuries"
When the word is used alone, without context, it is impossible to determine if it is being used as an insult or not.
A similar example is "oriental". On its own, it is not an insult. It can refer to a rug. If a British person uses it referring to a person, it is not a slur. If an American uses it, it is.