I proactively monitor new account sign-ups for signs of being a spammer. I can assure you that 99% of spam-bots do not get through due to a couple of road-blocks we have implemented a year ago or so.
Most spammers that get through are humans, which are difficult to detect or stop. However, as I mentioned, there are a few ways to tell and when I do, I stop them before they get a chance to spam. Without this daily routine, we would see a lot more drastic spam activity. Just check any other web hosting forum out there - some are covered in spam!
Great moderator candidacies are hard to come by, but I am already keeping my eyes open for 1-2 new folks who would be able to help. I prefer they are from time zones not filled by our current staff, who can react to spam reports quick. At most, spam is present for bare few hours before its removed.
PS: Removed spam should NOT affect your forum ranking stats. We appear like a "small" community on the outside, but we are quite active on the inside.