In the last 12 months I haven’t found a single false positive in the _spam_ folder of my mailbox. I still receive some false negatives, but that doesn’t bother me. No false positives means that I am able to change my processing workflow. Until now, all spam ended up in the spam folder, which I checked for false positives once a week. Today I changed my mail configuration to discard all messages flagged as spam. This saves me about 15 minutes of work every week!