I shot a 350 pound bear last fall in a huge spruce swamp. With trails all over. The bear came in right behind me. You mean to tell me she didn't smell me 15 feet up there?
Maybe it did... Maybe it didn't. My point is not that you can't kill a bear if he smells you, its that you will kill more and bigger if they don't.
I have had bears see or smell me and come in anyway. Also have had them see or smell me and run and never come back... Doing things to maximize your success is better than doing things that will spook some or most of the bears.