I suggest implementing (if possible) a system where if the person posts more than 3 or 4 posts with the same title/contents all of hits posts for the past 1 hour or so are removed.
Been suggested numerous times. Problem is there are new legitimate users who can easily post that many posts in the time frame.
Easier for me just to wipe it all away with a single click.
The automatic filters are constantly being updated. It's just that spammers are also updating what they post. There is no one solution - just a combination of things.