What does it mean that it was a no good copy? Did you get your money back for it? If it's in a sealed package, Amazon is just acting as the reseller, they did not make it and if it was bad, it was just as likely to be bad if that box was shipped to Staples or sold directly from their website.

Of course, if you are buying from another company through amazon, then you may or may not get a good company.

I would believe there is about a zero chance of Amazon selling anything but legitimate copies of software (assuming you are actually buying from Amazon)