An important factor missing in evaluating bear spray effectiveness is whether or not the spray can was expired. People may not know it’s only good for about a year and at a cost of over $30 they may try to use it anyway.
I just had a young black bear the size of a large dog come onto my back porch and front porch right up to the sliding glass doors. He didn’t try to get in but if he did I wasn’t holding a can of spray.