They will even show you "fake" problems your computer have trouble with but in order to fix them they will ask money and this is the fraud. These programs don't do anything else than making real errors on your computer if you keep them without paying the amount of money they're asking for. A good security program like Malwarebytes can easily detect them and remove them and also try to fix the mess they created (e.g disable task manager, registry etc in order to protect themselves from being removed).
Always remember, if a program that you have never downloaded/install comes up in a nice morning telling you're infected with 800+ viruses and at the same time is extremely annoying it's nothing else than a rogue application and its target is your wallet.
Usefull tips to define that a program is a rogue program:
(1) Extremely annoying.
(2) Asking for money every 5 minutes (in some cases less than 1 minute).
(3) Refuses to minimize or close.
(4) Engrish (English text with alot of mistakes and funny explanations about what settings do).
(5) Comes up doing scans and finding problems, every time your Operating System (Windows) are ready to use.
(6) Settings that they're completely unreal (e.g "hard disk error resistance" (this term was used in a rogue application about hard disk care there isnt such thing as error resist and you can't fix hardware problems using software obviously).
(7) Showed up after browsing in some weird websites.