Just an idea to add to your many site upgrades if it sounds interesting to you.
I personally believe there are a couple of people who rate stories as '1' without reading them.
The current program tracks the rating that a reader gives a story. It seems as if it would be a fairly simple addition to that section of code to create a 1-Bomber file and add the reader account, Rating Date, Author, and Story Name to the file every time someone rates a story as '1' (or possibly less than 3).
If a single reader is 1-bombing authors in general or a particular type of story, analyzing the file would let you know who is creating what many feel is a problem. The new code could include an automatic purge feature when a rating is more than 'X' days old and it can have an auto-reporting feature that reports reader accounts that exceed a threshold level of more than 'X' 1-bomb ratings.
The second half of the problem is, 'What to do with the 1-bomber?" That determination I will leave up to you.