With what goal? Giving campaigns the choice to accept spammers but not scammers? That doesn't make sense, neither one should be given any incentive to post.
The idea would be that campaign managers don't allow either. The distinction would be for dealers who know yellow (orange or whatever) is not related to trading trust.
If this will be enforced on all campaigns (including "Bounties"), I totally agree this is a very good solution. Your
other idea to disable signatures from anyone with a DT-spammer-tag instantly takes care of this.
Giving a "spammer" tag is not going to help. People running the campaigns will just add naturally the rule "No red trust + No orange trust"
Then what? People will continue to complain because they now have a spammer tag which gives the same result of the red trust for their activity here.
True, they'll still complain, but a spammer-tag fits better than using a scammer-tag for a different purpose.