All the posts from complaining Newbies without any merit prove the system works. I don't think bounty spammers will ever get a vote in it.
I found Newbie with 2800 posts and 0 merit:
https://bitcointalk.org/index.php?action=profile;u=1463210What do you think if forum will restrict all newbies to post active links? This might help with the massive spam.