Is your product idea a winner? Of course. Yeah, absolutely. Definitely. Why not? All answers you can expect from your local hobbyist inventor (and possibly yourself) when asked if anyone is sitting by the (smart)phone waiting for their latest, greatest product. But is there really such demand for a drone that delivers books or a pneumatic tube that shoots you across California? Some simple tests will tell you whether you should keep on down that road, or change direction.