You can make them work in a "tractor" application - reverse the brushless motor by trading any 2 of the three leads - the motor will spin "backwards" (clockwise from the front) and the prop blade profile will be correct
This is a problem since most planes are designed with thrust angles built in for a standard rotation tractor prop. Spin the prop the opposite way and you are eliminating the purpose of thrust angle... Bad idea
You guys are also forgetting the most important point about this pusher prop. Reversing it to be a tractor prop would lower the thrust dramatically. Being thicker on the leading edge and thinner on the other. Plus the curve of the prop makes it useless as a tractor prop! If you Dyno this prop in clock-wise rotation, amp draw is 2/3 less and so is the thrust output!!!