LOL, so, you want to say that people without paid signature can't be spammers? Interesting logic, but unfortunately you're wrong. In reality, big part of spam comes from Newbies who can't even wear signature. And do you want to say that question like ''How Do You Make Money With Bitcoin?'' isn't spammy? I don't think so.
And before complaining, what you have done to eliminate spam? Have you ever clicked ''Report to moderator button? Because mods aren't robots who work here 24/7 and they can't check every single post made by forum users.
P.S. Watch your language.