As per this answer the community user bumps questions when:
Note that the posts eligible for bumping are those scoring >= 0 that have gone at least 30 days with no activity, have at least one non-deleted answer scoring 0 and none scoring more than that, and no accepted answer (also, they can't be locked or closed).
I'd like to suggest that questions with a negatively scored answer should be bumped as well, the reasons I'd put forward are:
If the question is actually a decent one that's received a poor answer it should be bumped so someone can provide a quality answer.
If the question is low quality one unlikely to get a good answer it should be put in front of the community again so it can be closed.
Maybe these could be given a lower priority so it wouldn't affect larger sites like Stack Overflow, but on smaller sites where community bumps can be less frequent at the moment these questions often get left in limbo as unanswered questions.