nestork wrote:
In the case of hot water heaters, the manufacturer will encourage the
plumbing companies that sell it's heaters to offer an extended
warranty.

That's because they know that it's seldom that anything goes wrong
with their heaters during that first three years, and so it's not
exactly a "gamble" to warranty the heater for that extra time.

I bought a mouse pad at Best Buy. The clerk offered me an extended warranty
for only a quarter.

I passed.