One exception I made recently is for an mp3 player I really like to run with, but seems to have a lifespan of about 18-24 months--battery, headphone connector, screen, something. Usually I wouldn't buy an unreliable product like that, but there really isn't a good alternative anywhere near that price ($36), so I figured I'd live with replacing it as needed. Then I noticed that Amazon offered a 2 yr SquareTrade warranty for $3.65. Reviews on the warranty service were good, so I bought it. 14 months later something went wrong so I filed a claim. Later that day they sent me a FedEx label to print and told me to ship it back, and once they received and verified it, I'd get my $36 back. About two weeks later I got the money, as an Amazon credit IIRC.
I bought another warranty with the same replacement product, but it went unused. I'm still $29 ahead. The key for me was that it was a product I really wanted, but not great reliability, no good alternative, and it wasn't a killer to me if it did conk out--unlike a car that you don't want failing far away from home. Also it was easy to make the claim by mailing it back in, and they weren't screwing around with repairs, or sending me a refurb that might have it's own problems or be outdated when I made the claim. I got my money back. It's small change for me either way but I'd apply the same principle at any price. I just don't think there's too man deals like this around, and I don't think I've bought a SquareTrade warranty on another Amazon purchase.