I have no idea whether
DVC would bother to do this or not, but it would be done by AI. In theory, it (AI) could constantly crawl around the data related to frequent bookers or flagged accounts looking for, well, anything it wanted. One human could monitor the whole thing and evaluate the results to decide whether further action was warranted.
I know Disney's IT is the butt of many jokes, but I've got to assume Disney is following the same path as airports, professional sports arenas, etc, and adopting facial recognition technology to streamline the park experience even further. (I don't need to scan anything when I enter my local MLB stadium. It knows who I am and whether I have a ticket.) That info, combined with DVC bots monitoring reservations (and reservation holders), would give DVC all the info they need, assuming they have some policy/goal in mind re:rentals.