Hanging the food this way, there's just no tree nearby, so they can't figure out how to get the food. Of course, it helps that we don't allow food anywhere near our tent. We never eat anything in the tent. Also, we're super-careful not to spill anything, especially anything that would smell really good to a bear. If you spill hot chocolate or bacon grease around your campsite, you may as well not go to bed, because a bear is sure to find it.
Bears can smell better than dogs, and they can see and hear pretty well too.
I turned and saw Sean, but it wasn't his voice. He'd brought yet another JMT hiker, the one I had heard telling the young girls that this was his annual physical. His name was also John. Matt wore a Mexican straw hat, so we dubbed him Juan, for euphony. I keep my food with me, I mostly camp above tree line, where there isn't much natural bear food, so they don't go there much, and I growl.