True, words change. On the other hand, in cases like this the real question is why words change -- why gay is drifting towards being a general pejorative word, or why negro became pejorative enough that it had to be replaced by black, and that one in turn is being phased out in favour of African-American and the like. The fact that words change isn't interesting in itself, but what these changes reveal about the hidden values in the society is.
Nfr