One of the challenges for Zapread is building an incentives system for posting quality content. Any incentives system is hard to build because people will always try to game the system.
For Zapread, I am trying to build an incentives system such that the payoff for bad behavior is lower than good behavior. The Nash equilibrium must be biased toward good behavior. By having content voted down or up, and giving secondary and tertiary payouts (groups and communities), there is lots of incentive to not spam content.
Watch this documentary for a great explaination of the problem!