These days some dishwashers have a built-in web browser, and those are always vulnerable to hackers. In this case, the professional dishwasher can be hacked into giving up the admin password. Once a hacker gets a hold on that, they can install malware on the device or just program the dishwasher into wasting a lot of water.
If you notice a suspiciously unwashed dish in your favorite restaurant, it could be a fault of a rogue dishwasher! Thank you, the Internet of Things.