Language is a living thing, regularly pruning words that once had benign meaning ("retarded", for instance, was a medical term for "slowed") after they take on connotations beyond their original point. This process is not just window dressing or political correctness but rather a chance and provides a regular re-evaluation of whether we are saying what we really mean.
The difference between Sarah Palin's reaction to Rahm Emanuel's ill-advised use of the word "retarded" (directed at liberals), and Rush Limbaugh's use of the word (directed at advocates for the mentally handicapped) speaks volumes. When it was reported that Emanuel used the word in a private meeting -- one time -- Palin quickly took to Facebook and, mentioning Emanuel by name, called on President Obama to fire him. When Limbaugh repeatedly used the term on his radio show, Palin did nothing. Then, after being goaded by commentators, she had her spokesperson offer a generic criticism of "demeaning name calling," never mentioning Limbaugh by name -- and even had her spokesperson phone Rush to assure him she hadn't used his name. Then, in an interview with Fox that aired this morning, Palin defended Limbaugh's use of "retards" as "satire." Which it wasn't -- unless I'm missing the humor in calling a meeting of advocates for the mentally handicapped "a retard summit."