I think it's just a matter of time. While we do have thousands and thousands of members here with existing ranks to be able to participate in signature campaigns, the new accounts that are created for the sole purpose of ranking up to (a)join a signature campaign and (b)farm ranked users will become less and less common. I think in due time, signature campaigns will have fewer selection of participants to choose from, especially as the existing pool stops posting because they find it too difficult to rank up their accounts.

Yes, there's an underlying problem with signature campaign managers who manage these campaigns to low standards, so may I propose that we unofficially set a standard system to only allow acceptance of users with a minimum level of merit? This system can be enforced at a later time (after fair warning is given) by having several DT users place a red tag on the profiles of signature campaign managers who do not adhere to this new policy. It can be removed at a later time, but it may be an easy way to identify which campaign managers obviously don't give a shit about the level of quality of the campaign's participants' posts.

Yes, this is a bit of work to enforce, but it's a hell of a lot less than trying to monitor URL types from any given user's signature.