Frequently though people with -1 to -10 karma on a comment were just saying something that went against the hive or even dared to question it.
As an experiment sometimes I’d say something slightly against the tide, nothing even provocative. It would get downvoted into the basement and I’d see it start slowly then it would get pigpiled on. Then I’d post the same comment, say, a few hours later and it would be strongly upvoted. The same pattern of slowly getting upvoted and then rapidly increasing.