In one of his lectures videos posted on line, Tom Smith (bear expert) tells a humorous story about his bear bell research. People buy boatloads of bells to scare bears. Smith tested their efficacy and found bears didn't give a hoot about bells, but were keenly aware of the sound of a breaking pencil. Another study I read found that bears were indifferent to everyone's favorite bear repellent - banging pots and pans. The point made by both researchers is that there are loads of misconceptions regarding bears, often perpetuated because they make sense to humans who never consider if they make sense to bears (or if they do, are not in a position to know). Reading the posts in this thread remind me of this phenomenon.