SpywareBlaster doesn't scan and clean for spyware - it prevents it from ever being installed.
How? By setting a kill bit for the CLSIDs of spyware ActiveX controls, it prevents the installation of any of them from a webpage. You can run Internet Explorer with Active-X enabled, but you will never even get a Yes/No box popped up, asking you to install a spyware Active-X control (Internet Explorer will never download or run it!). All other Active-X controls or plug-ins will work fine.
More info:
hxxp://www.wilderssecurity.com/spywareblaster.html