This reminds me of one of my former ESPN co-workers - Mike Davidson[1] - who founded of one of the first community news sites (Newsvine[2]) back in 2006.
Newsvine had comments and upvotes and link submissions and posts - it was very reddit-esque except it was focused around the news. The team had to have a way to deal with spammers and trolls. They found the most effective way was to flag a user as a troll on the Newsvine backend. If the troll flag was set to true, Newsvine would add a random 10-60 second delay to every page load for the troll's account. IIRC it solved the problem pretty effectively.
Newsvine had comments and upvotes and link submissions and posts - it was very reddit-esque except it was focused around the news. The team had to have a way to deal with spammers and trolls. They found the most effective way was to flag a user as a troll on the Newsvine backend. If the troll flag was set to true, Newsvine would add a random 10-60 second delay to every page load for the troll's account. IIRC it solved the problem pretty effectively.
1- http://mikeindustries.com/blog/
2- https://en.wikipedia.org/wiki/Newsvine