Smudging to cleanse vs an offering

Why is it that smudging is used to cleanse but at the same time demon/God’s ask for some of the same herbs for an offering? Is there anyone who might have an answer? It was just a thought. I’m constantly seeing these shows of so called demonic totureing people, although by now we know it’s usually the people who have brought them in… Smudging is a common way to make perception of the beings non existent. I just find it a bit weird and the only logical explanation I have had is by the intent of the person using said herbs.