Ok, I got it, the idea was not good.
I know it's possible to turn off signatures or to block them partially using a script.
The idea was to change the behavior of some posters, just like signature campaigns changed it.
I will try to work on a better idea

The whole forum staff and a lot of high ranked users are also trying to find an ultimate solution for the spam (See the merit as it was the first official answer to the problem).
So don't worry, you are not alone, and it's not only your job to solve this situation.
Every idea has pros and cons, but in the end, this will have a solution or the forum will slowly fade away...
The first and most urgent problem is regulation the bounty managers but there's nothing average people can do in connection with this... but we'll see...