Burning can cause all the problems listed above. Scraping works okay but blades dull quickly from wire and metal tinsels. It also scrapes the finish off the hook.
The most effective method I have ever seen or used came from watching Ron Lucas at a tying show. It was a head slapping "now why didn't I think of that" moment.
Take a small pair of flat blade pliers without serations on the jaws. Starting either at the front or the back of the fly put the fly between the plier jaws and squeese really hard. You will feel the materials breaking as you squeeze. Progress down the hook till you reach the other end. This works so well you won't believe it. Wire, tinsel, thread, dubbing,,, everything compresses against the hook and seperates. Don't do this with the hook in your vise jaws because you have to squeeze very hard and may bend the hook if it is captured in the vise jaw.
It only takes a few seconds and it does not hurt the hook.
TC