I think the rain kind of cleanses the air of other smells and reactivates the bacteria in the bear scat to where the scent is more pronounced. They eat just about anything they can scavenge. I am sure that much of the scent comes from eating rotten carcasses of dead animals they find. I can’t imagine that smell coming from berries. Plus berries are very seasonal. The rest of the time they forage for grasses, nuts, grubs and carrion.
Yeah. Pickers, for huckleberries, truffles, mushrooms, etc need to be alert for bears. I notice that certain dog breeds like smells. Particularly bird dogs and retrievers like to "get a scent" on them- like rolling in whatever dead creature they find in the brush: dead cow, deer, fish, etc. Nasty. But evolutionary? Hide their own scent?