This has been discussed over and over and over again...
You lost 20 ether, your bad!!, you invested in a scam project willingly,you weren't under any duress,so you do your homework properly before investing next time...

As for removing paid signature advertisement,its not gonna happen,due to the traffic/revenue it brings to the forum.
If the one merit>Jr member rank isn't sufficient to quell spam, then a stricter rule could be implemented,maybe 5
But bitcoin talk wouldn't stop signature ad

It's not the duty of the forum to protect it's members from scam, you can simply learn how to spot/avoid scammers in here.
You can take a horse to the water but can't force it to drink water