See, I feel as though I have always followed the above listed rules as a boarder, and I had a CRAZY BO once. She stole a halter from me - I proved it. It was nuts. It was just a nylon halter, nothing fancy - but, boy, did she ever want it.
In all honesty, I've had more problems with other boarders than I have with BOs though. Horse people can be NUTS sometimes.