Best trick I have seen is putting the feeder up on heavy duty and tall stilts or poles so they can not reach it. Of course this means you have to carry the feed up a ladder to stock it, a big pain in the butt.
If a bear smells anything good he will go through great lengths to get the good smell. I have seen them shred iron boxes, pull down trees and even dismantle structures for something to eat or something they think smells good.
