I have Lavasoft AdAware SE Professional, Spybot S&D and SpywareBlaster installed on my system, and run them everytime the computer has been online or at least once a day. I also tend to run them after installing new software.
I'm not surprised that it found some things the others missed. I posted a link to a test of anti-adware software a couple of months ago (
here ), and the outcome was that there was no single perfect spyware killer: they all find some and miss some, although the forum favourites, Spybot S&D and AdAware, largely found the same stuff.
As it happens, the best-performing spyware killer in that test was Giant's Anti-Spyware product - which was subsequently acquired by Microsoft and became their beta anti-spyware software...