I was recently a victim of the negative moderation ban
(ie. my subnet was prevented from posting comments for
several days due to excessive negative moderation).
The cause of this were a few comments which received
lots of both positive and negative moderations due to
their contraversial nature (and some moderators clearly
moderating based on personal opinion rather than
comment quality). If nobody had moderated the comments
positively tthen they would have dropped down to -1 and
stayed there, with perhaps 2 or 3 negative moderations.
The problem was that with people moderating the
comments up, others were able to continue moderating
them down leading to excessive negative moderation.
The upshot of this is that people that post comments
that cause disagreement among moderators are extremely
vulnerable to this ban, that can't be desirable. I
suggest this mechanism take account of the number of
positive moderations received by comments, rather than
just (I assume) counting the negative moderations.