On Thursday, September 11, 2014 10:23:47 AM UTC-4, William Sommerwerck wrote:
Mythbusters, anyone?

To the best of my knowledge, there is nothing in any motor that
//mechanically// favors rotation in one direction. "Forwards" and "backwards"
are determined electromagnetically, not mechanically.

I've seen (very cheap) brush-type motors that had asymmetric brush
springs, that would possibly buckle if the motor was reversed.