Beware of 99% of the warranties out there. There are so many aftermarket or additional warranty plans out there, and they are being pushed on customers hard by car dealers, phone solicitors and pamphlet pushers. If you buy an extended warranty from your dealer as your manufacturer's warranty is running out (which I don't recommend, by the way), it's most likely legitimate. They may do a little fast talking, but you won't be scammed. Just read up to see what you're really getting for your premiums. What are bogus are the type of warranty that is sold to you over the phone, with no inspection of your vehicle. A huge percentage of the time these warranties will take your premiums and leave you high and dry when it comes time to do a major repair on your car. If you are considering adding warranty protection, read all of the fine print and do a LOT of research online to see what other people think about the warranty.
Generally any warranty that doesn't need to see your car first is suspect. How can they guarantee your transmission if they don't even know whether your car is in running condition? Seriously, think about it. If you buy one of those warranties and your transmission does go, the fine print will burn you and your repair won't be paid for.
The bottom line with any contract, especially one that will be costing you money, is do your homework! The internet is your friend. If you dig a little you'll find mega complaints with the quickness on any warranty company that may be less than legit.