This is an old thread but I have been checking out a lot of motors lately and they can be different. I have a few different Mabuchi's, Radio Shacks and Maxons. The Mabuchis all spin counter clockwise except for a smaller one I have which spins clockwise, one of the RS motors spins counter while the other spins clockwise, the Maxons spin clockwise. The directions of these motors are all with positive to positive connection. Guess it just depends on the motors design unless the manufacturer screwed up the + marking haha.