I have sprayed 100's of dogs in my mailman career. Almost very letter carrier in our town has. I always knew which way the wind was blowing, unless it was a light wind not enough to matter. However, Halt is not bear spray and I have no experience with it. Halt can be purchased at any bicycle shop (it is NOT bear spray, nor mace) it is cayenne pepper spray.
Yep, in California not a single grizzly has been sighted for decades.
No person has ever been killed by a black bear in 150 years of Yosemite park history.
Many hikers I know, and those I have seen, hang their bear canisters (I do too). On the other hand it is easy to see all the canisters in the trees, the ones on the ground you don't see, so maybe lots more folks actually do not hang them than those who do, I'm not sure.
There are places on the net to see how to properly hang a bear bag or canister, so that the smartest bear in the world will not likely defeat the system. But it is lots more effort to do it and sometimes the bear wins anyway.