I would also add that both disused:*=* and shop=vacant are perfectly valid tagging schemes. One is for a non-obvious location that was closed but might reasonably be expected to reopen as the same or different amenity; while the latter is for an obvious one, like vacant street-facing shops or empty room in a mall that may or may not be reopened. Of course, details vary, but in general shop=vacant are quite obvious as you walk down the street and see a closed venue.