"Regarding how Facebook identifies hate speech, the Times reports:

'The guidelines for identifying hate speech, a problem that has bedeviled Facebook, run to 200 jargon-filled, head-spinning pages. Moderators must sort a post into one of three “tiers” of severity. They must bear in mind lists like the six “designated dehumanizing comparisons,” among them comparing Jews to rats.'"

For what consistent rules they do have, they're not allowing their moderators to use common sense:

"Some moderators vented their frustration to the Times, lamenting that posts left up could lead to violence. “You feel like you killed someone by not acting,” one said, speaking anonymously because he had signed a nondisclosure agreement. Moderators also revealed that they face pressure to review a thousand pieces of content per day, with only eight to 10 seconds to judge each post."