Indeed, it isn't to be a big issue for them. However the thing it isn't the main tasks of their job, maintain and moderating ANN on bitcointalk could be count as a voluntary task (which isn't mandatory) and by such kind of thought most people would tend to not do that unless they got additional benefits from it.

I guess to get rid of those beggars is not much different with kick out all of the spammers on this forum which is almost impossible, the best way might be just to reduce it to some extent.