A glance at the tag "hindpaw" ( http://e621.net/wiki/show?nordirect=1&title=hindpaw ) reveals that everything related to the word "foot" is aliased to it. It works for any situation in which an anthropomorphic is involved.
However, this isn't just a furry image archive, and it just looks ridiculous to see the word "hindpaw" tagged under an image of a human. The alias just isn't valid for large portion of the images it's applied too, and ought to be nixed.
It's even arguable that "hindpaws" ought to be aliased to "feet" if we wanted to consolidate the tags and avoid having to use both. It would certainly make more sense than it's current incarnation.