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.
This is a Miscellaneous Security application related to AntiVirusForAll and AVSystemCare. This product takes credit card information before giving the selling price to the user.
This is the most disgraceful product ever.
A non-computer literate friend was persuaded by popups first to buy it then to "upgrade" for an initial ?30, then another ?60 for the "upgraded" product. I spent last friday reinstalling his windows XP (new install rather than upgrade) after his PC had been crippled - so slow as to be unusable
After installing XP I ran Avira, and whether this is your favourite antivirus or not, it is free, it is effective, and it found 115 trojans and malware items. This after XP install had "formatted" the disk. I have never before seen this scale of malware on one PC
All this crapware was preserved as docs and settings.
One thing is certain - Errclean does not keep a PC clean - and paying for it amounts to paying for malware where we all know it is readily available free