Spybot and Adaware don't update all that frequently, however the definitions do.

Spyware keeps getting nastier and nastier. In the case of CWS, it will kill Spybot. I'm not sure if Spybot has released an update that will prevent that yet, but I know Adaware made some modifications so that it doesn't happen to their application. Anti-Spyware apps are constantly reacting to changes in malware, and there is no way possible that they can guess which tactic malware may employ.