Facebook should maybe take a lesson fron early ISPs like Uunet, Earthlink and a few others. Everyone except Uunet thought Uunet had a spam problem. Uunet would act on some spammers, but not the high volume problems. It turned out that Uunet had "pink contracts" some some spammers, and wouldn't turn them off.
Where is Uunet today? An odious memory, merged into MCI and forgotten. Corporations aren't forever. They can ruin themselves.