Filtering is more accurate if you simply correct its mistakes as they occur
If I have to correct false positives as the occur, this so-called "filtering" is no good to me at all, because it means I have to go through all the spam. Worse than useless. My existing filtering system is significantly better, because I am confident that 100.000% of everything filtered into the spam folders is, in fact, worthless junk. Additionally, *most* of my legitimate mail is filtered into various spam-free folders based on topic, list, sender or whatever. The only mail I have to sort by hand is the stuff that lands in my inbox (because none of my filters pick it up).
I don't want to correct my filter's errors continually. If I have to do that, it's not doing its job at ALL; *I* would be doing 100% of the filter's job, then.