I thought LED's lasted pretty much forever. At least, in car lifespan terms.
The Clear Corner lights almost look good enough to justify a conversion for my '92.
Nick
LEDs are no different than any other electrical component: they last as long as they're engineered to last.
I have customers who bring me plug-in LED bulbs as they fail. They typically last as little as several weeks to as long as several months. Overall, the plug-in stuff has a very high failure rate.
much like pbassjo said about paint, anyone can squeeze a paint gun trigger - the magic is in the prep and detail. if you buy an LED product, better be sure its engineered properly.