I have thought about and have suggested that we consider removing signatures from some of the lower ranks before. If we encourage/force campaign managers to only accept quality posters shitposters would have no where to go unless they significantly improved the quality of their posts. Things can be done but there definitely needs to be some repercussions for people running lazy campaigns.
The problem is that any non-technical enforcement (e.g. trying to strengthen campaign management vs. removing/reducing signatures) will require more staff effort, create more abuse/loopholes, etc possibly to the point of defeating the traffic benefits.
I'm all for making campaign managers responsible for the crap but how would you enforce it? Allow only approved sig campaigns similar to how banners are auctioned off, and require them to hire proper managers? What if users start wearing rogue "unapproved" sig ads perhaps contracted outside of the forum? Who would even decide what constitutes an ad? E.g. is my sig an ad?
The whole idea if sig ads is just a bizarre concept that's impossible to balance properly. Especially when you consider the massive range of incomes across the world. 0.1 BTC can be either a modest dinner or a monthly income.