I agree with a lot of you in that some service contracts can be a waste of $$ but some are actually worth taking a look at if you can get a decent deal purchasing it.
Most service contracts are inclusionary which means that only the parts that are listed in the contract are covered. Those types are typically worse than the exclusionary service contracts which cover ALL parts except the specific items that are listed on the contract. They are harder to find and usually run a bit more $$ but are in every way a better deal in my opinion.
They're not all bad