Removing signatures altogether is something we're also discussing. Personally, I'm at the point where I think that's going to be the only solution to stop all the bullshit and hassle that comes along with having them but we're trying to find a workaround too that suits everyone.
if people trying to log on from previously banned ips have to pay up, would it not make sense for people who organise sig campaigns to post some type of bond to be able to host one?
I dunno the ins and outs of how the signatures work, but maybe they can include some code that allows a moderator to shut the campaign down if enough of their participants are posting junk.
there are campaigns that are run well and are diligent about who they admit. that would incentivize all the rest to stay in line.