I'm with Kevin. Remember, this is insurance for major repairs, not an investment program and not a way to avoid all out-of-pocket expenses. Do you expect to "break even" on your homeowner's policy, or your car insurance? Of course not. So don't let the sales guy persuade you that their extended warranty will "fix everything that can go wrong" and "pay for itself in a couple years". It might, but the odds are against you from the start. A few will collect more than their premiums, but most will not. It's the nature of insurance.
Sure there are some fairly expensive things, e.g. air conditioners and fridges, but they don't fail all the time either. And they won't be covered 100% either. Not just the deductible, either. There will nearly always be parts of the bill that aren't covered, for various obscure reasons.