Hal, I'm right with ya man. If a guy does his trap prep correctly, there is no reason to question it at the first sign of a digger. I've taken 4 very large coons on the farm I first had some diggin going on, now the diggin's stopped.
Now, I'll quickley share a story on the flip side of this. Obviously there are going to be times when we will encounter a digger fox. I encounter this when I move into a new area that was trapped previously by a trapper who educated the fox in that area. For a couple days I had a few sets dug up on a particular farm and by the tracks in the dirt, I was quite certain it was a fox. Yesterday I caught a huge male red fox at a set that I simply repositioned the trap to where the fox was standing while he was digging me out. I've caught 2 such diggers this year but I will agree that in most cases it's a coon.
Now one more thought. At another farm I had a set dug up two days in a row. The tracks in the dirt were very small and I really had no idea what I was dealing with. On the third day I caught a grounhog at the set. Hmmmm, I don't know? Anything's possible.