-3.3 ALL_TRUSTED Most of these unmarked spams hit ALL_TRUSTED with a default score of -3.3. It almost completely discounts the SURBL score hits.
If you have spams that are matching ALL_TRUSTED, you've got trust path problems. That really should only be firing off for internal mail.
You should consider that a serious misconfiguration problem. Start setting your trusted_networks manualy if you have to, but run a message or two through spamassassin -D to see what SA is considering trusted by default.
Problems with the trust path are the root of your problem, I'd address those LONG before touching the surbl scores.
The surbl scores really aren't low anyway, you're just used to the massively high 3.0 they were assigned prior to being balanced and tested. The scores they have are quite adequate, see the discussion in the archives from weeks ago between me and Chris S. on how scoring works and how this impacts the SURBL lists and why WS is so much lower than SC and OB.
SA's rule score assignment system tends to compensate "overlapping" rules, and most of the SURBL rules tend to overlapp and fire off in groups. SA effectively wound up assigning high points (over 8.0 total) to surbl as a big lump, then subdivided it based on list performance. That's not how it literally works, it's a lot more complicated, but the logic used has the same basic effect.
If you really want to tweak them up, adjust OB and SC up half a point and WS up a quarter point. Be aware WS has a higher FP rate than SC and OB, something that's being worked on but is why it scored much lower than OB and SC in the first place.
