On the inari side of things, i.e. the fox-spirit side, there are two theories about this, but there is one that is more likely. One theory says these are inarizushi because they look sort of like foxes, being brown and sort of rumply (=furry), but this is unlikely. The other is that they are tricksters: they look like one thing but really they are another, thus inari. This is (as I understand it) the probable solution, if a bit simplistically stated.

If you want thorough information about the linguistic provenance of abuurage Sarah can provide it, but you have to tell me what exactly it is you're asking. Get technical. She'll roll her eyes, but she'll figure it out (she did go to U of C, which you may have heard of...), and if she can't we have a pal in the anthro department who can.