Question about managing tags

[Rellwood]

So I finally got around to setting up (some) of the tag manipulation rules when adding books. I have a ton of old tags that seem to keep showing up when I move books around in libraries and just using the tag manager doesn't seem to work. The rules I am working with right now are just removing the tags. Best first step I can think of since there are so many changes that need to be made.

My question is, when are the rules applied? Does the book have to be imported through "add book" or can it be when copying or moving between libraries?
I know that if I have a tag that is added when importing books that tag shows up whenever I move the book around, but I am seeing tags I listed as being removed - not being removed when copying to another library.

I was thought to just save myself a headache and copy all my books to another library in the belief that the tag rules would apply. Then bring them back, all organized.