I see the spam as a moderation issue and think more (active) moderators and admins handing out well deserved bans are a solution.
Or..
Influential members such as yourself and others that feel the same way can easily speak up against them and force their hand to rectify the situation..
Take your greivences directly to the campaign managers and above their head if necessary in whatever company they are working for..
If you feel so strongly about it you could start tagging managers and company accounts that refuse to cooperate in reducing the spam they are employing..
I bet they'd shape up real quick if they started getting tagged themselves..
"allows spam in the sig campaign he manages"
"this company won't stop spamming our board"
Trusted/influential member: "Hey guy..If you don't stop the spam emanating from the campaign you manage I'm going to leave you red trust and go tell your boss to fire you.."
Trusted/influential member: "Hey guy.. If you don't fire and replace that lazy campaign manager of yours that is allowing spam to emanate from the campaign he is running, which is a responsibility of your company, then I distrust you and your entire company for allowing and promoting this trash"
(Trusted/influential member:) or even group of average members..
Email/pm/post bomb em like congressmen when you want your voice to be heard about what you think should or should not be done..
There you go, problem solved with no government, either they fix the problem or you rightly so wreck the reputation of their company..
I bet all it would take is 1..