I have accounted for this with the mechanism that modulates effective reputation score via mute/follow. More than likely the trolls are an equal population to the anti-trolls, and most likely, because of the incentive structure, the ones in between will join the antitrolls.
Calibrae will be tossing out the bandwidth limitation system for a transaction limitation system that is based on the product of reputation coefficient multiplied by stake. Baseline accounts will probably have something like 12 transactions allocated a day, and at zero reputation, or with sufficient mutes on an account, zeroed reputation, the trolls will only have 1 transaction per day.
New account signup will create accounts that are below the baseline of new accounts created in the migration process, similar to 'fremium' accounts. They will have a quarter the allowable transactions (I still have to work out the best numbers for this), and will be far more vulnerable to being muted and flagged into calibrae 'jail' of 1 tx per day.
With this scheme there is no need to limit the rate of account signup, because it won't take long for signup spammers to realise there is no power in these new accounts that they can really use. The interface will make downvote and upvote lists more visible to users, and place a handy 'mute/follow' button on the both, so if you do/don't like people's votes, you can suppress or boost them.