Ad-Aware 6.0 SE was an old good one in it's day as well as Ad-Aware 2007. Since then Lavasoft has gone strictly retail. SpyBot S&D just like Ewido have become outdated while AVG is generally the best free antivirus program found.
For spywares/adawares Spyware Terminator the real one seen at http://www.spywareterminator.com/ that is not the bogus program using the same name places it's own active shield around the system registry like a firewall. Any changes even when going to remove a program will see the allow/deny prompting.
When first comparing that to Ad-Aware 2007 at the time one would find what the other missed. While Ad-Aware is out it still shows no one program will ever be the one that catches everything. "Mutiple layers offers protection from multiple problems" is the rather simple solution.