I think full mask sporrans are perfectly suitable, being as they are a solidly traditional piece of Highland attire. It's not really "fashion" at all. In fact, "fashion" has more to do with all the other non-traditional sporrans people are wearing nowadays.

That said, I do think that full mask sporrans can easily go over the edge. A badger, fox, or other traditional and normal animal is great. Skunk is pushing it a little (for me, anyway).