Spam is no longer a moderation issue as I've seen many users being negged for spamming so that they cannot participate in signature campaigns.
'Many users'? Could you please PM me a list of these users. Spam is still an ever growing problem on this forum.
The whole TRUST system needs to be remodeled and some rules should be set to avoid this misuse/abuse.
If it's a web-of-trust system, then leaving a rating to someone, because their behavior (spamming) is untrustworthy, is an appropriate use of the system. The problem with the current system is only that it isn't fully defined, although this makes it easy for the community to adapt to new trends and act accordingly.