Since StoneCold locked his thread, I'm bringing this post here because it is what I was thinking when I read it there. Sg1008 posted
The bears who do attack people are usually those who have their territories infringed upon by human activity, and who (through experience with people) learn not to be afraid of people; so when they see people (at a camp site, or somewhere where garbage and food are left around) they may become territorial.
Do you have any tips on how to tell the difference besides you're bleeding to death from the attacking bear?