I have been attacked by both black and grizzly bears, none of them were deterred in the least by any verbal comments I made or my scent which they couldn't have missed.
There is a bell shaped curve for everything including bear attacks, some will leave without attacking and the other side of the curve exists also, they will attack knowing you are a human. The griz that was after me was a 3 or 4 year old bear that was on my trail while I was running,  scent didn't matter, shouting didn't matter, I threw rocks madly to it's sides and at it which slowed it down as it went up on it's hind legs to look at the noise to the side. It got to 15 ft turned and left, I could hear it running in circles in the dry leaves just out of sight. Hopefully someone reading this can duplicate my escape but you never know about bears. I have also had sealions false charge me several times underwater, they can turn on a dime at full speed, you have to tell yourself not to panic and look for options.
(Bruce)