These are usually anti-spyware or security software applications that use various forms of deception and/or unethical means or show a history of negligent false positives to goad the end user to make a purchase.
In some cases these applications maybe downloaded with some form of unwanted software at which point the rogue application is offered to the customer as a way to remove the unwanted software.
Comment:
onlineregistryscan.org displays a fake scan upon loading the front page, then falsifies a report to coax the user into purchasing a product. User will be sent to secure.repair-registry.net, where the order form resides, unless the site is exited.