To everyone who thinks it's unfair, think about this, they are a proven scam site and you are promoting them meaning that there are more people that will see your signature advertising them and it's only a matter of time before these scam site will be seen by people who don't know anything about the site. In short, you are basically an enabler of scams in this forum.
You're right here but most of the people who are hunting bounties or in the signature campaign, don't bother to see what they are promoting. Their only interest is to get accepted in the campaign and complete the post count to get paid. None of them wants to promote scam but they only want to earn money.
Yes, once they know this is scam site, they should stop prompting it and remove the signatures ASAP.