three things
one, if we're really going for random annyoance, i volunteer this formula:
(negative if on the wrong side of a bill, positive if on the right side)(((5!/no. of voters)*(total word count of voter's posts/total word count of all posts))+pi or e or some cute mod)
encourages activity and takling, gives a reason to discourage voters (granted if the mob disappears suddenly the first part's too big), encourages people to try to vote with how it'll go, which means the mob can cause surprise upests.
two, since i actually don't agree with random annoyance unless it's amusing which formule aren't, i'd really suggest something like excal's rule or something creatively amusing to all involved
because while i like the concept of this game it still has the issue of being about as interesting as frozen pepper