[pellucidar]

Some spam is just thrown away, not put into your Spam folder, so there's some lost opportunity to disagree (and it's hard to judge whether you would have without seeing the spam).

Also, GMail is no longer good at detecting spam. It consistently puts my phone bill into spam, as well as other repeat emails I've marked as not spam. More importantly, I get bursts of actual, obvious spam in my inbox at least twice a month, possibly more often. Maybe Google has just given up and some other anti-spam system is better.