The quality of posting in the main section of the forum has dropped dramatically since I joined. Nothings going to change unless paid signatures are stopped though (and yes Im aware that Im wearing one but I dont post like the spammers present there).
Well that means you're okay with the paid signature campaigns but just wanted them to be spam free. It's not as same as you saying they should be stopped completely. If you were any serious, you'd not be wearing a signature at all. That's a good first initiative.
The problem is not paid signatures in general. When the merit system was implemented, juniors were removed of clickable signatures. But they can still have (non-clickable) signatures, and many bounties pay them for posting crap with those. So the spam didn't decrease (much?).
Signatures up to junior member of even to member have to be removed completely, and there have been other many good proposals that they will never be implemented or will take ages until they do.