We are never going to completely eradicate spam
Yes, and honestly i doubt any member of our community is hoping for that cause it is somewhat impossible, we could only possibly reduce it to a bare minimum somewhere along the line, i mean, if there is a 'multitude' of good/decent users and a couple of spam users who will prolly get most of their posts reported and maybe deleted every now and then, thus that will be just fine.
Signature campaigns have been around forever, however the quality imposed by the managers (at least the main sections) has become a lot better than it was five years ago.
Honestly signature campaign managers shoulder a lot of responsibility in the forum, some users might not notice it but they do, quite a lot of users are on a signature campaign, and many of these managers make it a criteria for the user to be a decent poster, i am pretty sure this has encouraged a lot of users to work on themselves and bolster their knowledge, so on one hand they get to learn a lot about Bitcoin, post quality stuff and then earn some 'pocket money' via signature campaigns; so campaign managers have a lot to play in the quality of posts on the forum.