New negative trust color:
Red color : Scammers Yellow color : Spammers
That seems like a rather *simple* change, that might just be effective enough. I'd be interested in hearing what others think about it.
Lets go one step further, don't call it trust, thats a marketplace thing. I dont necessarily distrust spammers, they are an annoyance.
Add a second way to rate users, call it
post score (or something similar), the system itself could even work the same way the trust system works (with only minor adjustments).
Might even add options to hide the post scores completely, if you do not care about that sort of governance/moderation.