--snipe--
Yes, maybe a test it's the better thing. Block the signature or limit the characters and see if the spam will end or not.. (I guess : yes of course !).
On the other side,most of the Gambling sites or any new bitcoin related Start-ups approach the forum for advertisement of their products.Vaguely,Signature Campaigns are the easiest ways to do it (apart from promo giveaways).Do you think such Start-ups would still approach if they're unlikely to get as much exposure after stopping the signature campaigns?
Yes.
They can buy one or more ad slot instead using the sig. campaign 'method' to promote their startup/site, I'm sure the spam will end ...