Did someone already answer my question about the possibility of idle masternodes? I asked if it is theoretically possible to have a masternode online that doesn't do the required work (intantX confirmations and mixing) but still receiving masternode rewards. There was so much trolling I probably missed the answer...
All nodes in the masternode network are in constant communication with each other. They are "used" in a deterministic order when there is "work" to do. This means that there are no idle masternodes.