One guy shared a story with me in NM about hunting way up in the hills..near water...and he had pinned some fake leaves to his DB. The bear was smaller than he wanted to shoot...but when it started chewing on and tearing off the leaves, he hollared at the bear and it about turned inside out...
Guess if they mess with a blind when you're in it, they'd do so when you're not.
Dunno how to bear proof a DB though...maybe someone will come along! Good luck. No small costs to have one repaired to that extent! :(