I use the plug-in kind, though as a previous poster said, getting refills is not a priority. As for the scents, I’ll only use things like white linen or fresh rain. If it’s at all sweet, I can’t stand it. So no spiced apple or vanilla or fresh baked cookies for me.
As for why, I just like the way they smell. I do have a cat and a dog, but I’m not trying to cover up their smells. I don’t think that would work anyway. The kind I get isn’t strong enough to overcome any smells in the house. It just adds a nice overtone.