One of the reasons that we have a learning spam filter is just as you say you spend your whole time chasing how the spammers have changed their mail today, or this week. My "learned" spam filter wards out about all my spam. It has had years of practice, but tell me. Do you mark your spam as spam in the filters or just do some arbitrary action with it so the filter gets no opportunity to learn? My observation is folk who waste time on manual spam filtering mostly do not mark the messages as spam. Nor do they execute the filter after junk classification. They then say the filter does not learn and their system works better. Without ever having really used the junk filter or it's Bayesian logic.