An interesting thing that Keith and Dylan have pointed out, is that even when someone is backing-it-in, or when steering with the rear (as mentioned above), to some degree the bike is still traveling in a straight line, and is not actually moving 100% in the intended direction.
I also have to agree with Bullet. If I was given a bunch of toys to play with and break, and not have to pay for them or fix them, I'd be experimenting with more than just rear wheel spin on entry.