I was camped fairly near some other folks, and they filled their bear canister with food, then stuck that into a nylon bag, which they then hung with rope very high in a tree. I woke up in the middle of the night with the sounds of their antics. The sow black bear came into camp, sent the cub up the tree, and the cub got to the rope. The cub chewed the rope, which sent the nylon bag and canister hurtling to the ground, or more specifically, onto the granite. The canister cracked open like a Mexican pinata. The bears scored, big time.
If those people had just left the bare canister out flat on the ground, it would not have been a problem.