Some are a good deal (for me)
I consider three things when considering the purchase of an extended warranty:
1. Past experience with the product/product type. How long they last, when we replace/updgrade/dispose of them.
2. Fragility/likelyhood of repairs.
3. Expense of repairs.
Warranties that have paid for themselves:
* Chevy Avalanche 2500 - Thousands of dollars saved in 4wD components, power window actuators, and steering parts replacements. Consideration #2 played a big part. The Avalanche is a big, tough truck, but being the outdoors-y type of family, we drive the heck out of it.
* Dell Extended Warranty and premium support on the Kids' computers for college. Paid for itself the first time my son's roommate closed the lid on a pen and cracked the display. Next was a lightening strick that zapped the network modules - replaced the motherboards. Daughter's new keyboard gets installed today. Three years to go :o) Considerations #1, #2 & #3.
Warranties that were a waste of big dollars:
1. Got them for all of our major Appliances (washer, dryer, water heater, & fridge), but never had problems during the warranty periods. Two years left on the water heater, all other a waste.
2. Two Harley Davidsons; no problems while the warranty was running. Only repair: $45.00 tail light part, and I saved on the service cost by buying a $6 tool and doing it myself.
My daughter just got a new truck - with a lifetime warranty on the drivetrain. She spent the extra money ($1000 through fleet sales) to warranty **everything** else for life, too. Not sure Dodge knows what they're getting into selling trucks to frugal teens.
Hope this helps.