You shouldn't believe everything you read on the Internet. Most people simply just ignore that advice and that's how Virus Sweeper gets into computers. Virus Sweeper is advertised as a warning indicating that you should use it to disinfect your computer. When users do download and run it, that's when Virus Sweeper takes over.
They even have a very convincing user interface that makes Virus Sweeper seem like an actual anti-malware program:
You can find removal instructions and a utility here.