No doubt, you would have come across news reports about how to get a free iPad scams like the previous year's Facebook ad scams that were rather widespread. This would be a major reason why you are hesitant to believe that offers here are legitimate.
Such ads often advertise for users' phone numbers that are used to subscribe to some service that cost around $10 a month. Although there are no official figures to say how many people have fallen victim to this, there was certainly a large enough number for it to be highlight in news reports and technology blogs. Some criticized Facebook for not being strict enough in vetting their ads, but let me tell you, Facebook have among the most strict ad approval process that I have experienced. Such scams create doubt to genuine offers from reputable companies.