Get a hav-a heart trap. If it's a skunk, you'll want one that is small enough that it can't raise it's tail

.
I would watch for a few days to find what type of culprit you have

. Both can do much more damage than digging in your plants. I don't think it has anything to do with your potting mix, I have used Fafard for a couple of years and it hasn't attracted any critters.
Sue