[paulat]

Some slang, and some slurs, lives on for many years, but most shows up for a couple of decades and then goes away.

Not true at all...the "n"-word has lived on for centuries...I know for a fact that "Polack" has (even though Wiki doesn't include the spelling, "Pollack.")

The ethnic slurs between France and Great Britain are legendary for going on for centuries. See Wm. Shakespeare.

I could go on and on down that list.

[discostu]

I aknowledged that some slang and slurs live on for a long time. But most don't. Most only last a couple of year, some make it a couple decades. It's the rare few that manage to permanently implant themselves in the language.