Skunk
There are 2 possibilities of skunk in our area: Eastern Spotted Skunk (S[ilogale putorius) and Striped Skunk (Mephitis mephitis). Since we only smelled this guy from our deck, I’m uncertain which it could be. The Striped Skunk is the most common and the Eastern Spotted Skunk is rarely seen in Wisconsin so I have to believe it was the Striped Skunk.
One of the signs is clawed-up earth, probably from their foraging for grubs. They are omnivorous, eating a wide variety of insect, fruits, small mammals, eggs, and seeds. They tend to use an abandoned burrow or a hollow log in spring and summer. In winter, they will burrow underground.
These mammals are not highly valued economically. Their musk is used in the perfume industry though. The odor is removed and it becomes the basis of the perfume/cologne. This is because of the musk’s ability to cling to a surface.
Nature Works and Wisconsin DNR EEK! sites have some good info and photos.