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 suppose that's a possibility but people would just complain when/if they didn't get their bond back. An easier option which I suggested would be to force people to use a trusted and reliable campaign manager from a list that the community could source in a similar way we do with escrows. If every campaign manager was very thorough and only allowed good quality users to join there would be no issue in the first place. At least this would almost assure that.
When people earn BTC from sig campaigns, they spend some of them mostly in gambling sites, some even save then spend them in cloud mining contracts (don't know why, most of those don't get you a ROI), others go to the market place and trade them for cash and the rest do altcoin trades. That's overall good as BTC changes hands a lot.
You do realize that the useless content that is produced by them is the reason for which people with actual knowledge regarding Bitcoin stay away from this forum? I couldn't care less about the few bucks that these spammers make and what they do with it. There are campaigns that do not care about this problem (e.g. BitMixer); thus the need to punish services that endorse spam.
That's why a good move from Bitcointalk would be to ban all sig campaigns in all sections in the forum except the Bitcoin and Altcoin market places imo.
As I mentioned before, if you're going to remove them from pretty much the entire forum it defeats the purpose of them in the first place so you might as well just remove signatures from the entire forum. Allowing them only in the Marketplaces would make those sections unusable.