Forum Moderators: phranque
For example, a lot of people got infected by a piece of spyware that modifies your hosts file in Windows so that google.com redirects you to a fraudulent website. It's believed this was done as a blatant example for all to see about some of the inherent security weaknesses in Windows because the website it directs you to also offers reliable instructions on how to undo what the spyware did. This is not something either Ad-aware or Spybot will catch.
In summary, spyware/adware removal programs are great and IMO an essential piece of software. But do not rely upon them to keep you safe. That's a job best accomplished by learning how these scammers use social engineering to get you to infect your own computer with their scumware. :)
Updated for clarity.