In the past I've been a long ways in to the back country wilderness in and around Yellowstone and Glacier National Parks. Had a couple of things happen while camped there that I still wonder about. These stories are interesting and something that should be taken in to consideration when venturing in to the national parks. I've listened to a lot of these kind of stories over the years and there are two pieces of advice that seem to be good advice and consistent. Don't go alone and don't go unarmed. The government doesn't want you carrying fire arms in national parks but I don't think you should pay any attention to those communist bastards and SOB's, just keep your weapons out of sight.
Thought I'd add that the government employees I ran in to when I was in the back country were assholes that seemed to like to bully people and were always looking for some thing they could chew your ass for.