Have you tried reporting those users to their campaign managers? It's like a lot of spammers just evolued to pseudo-goodposters[1] and are getting money by lowering the general quality of the forum posts.

[1] Not blatantly spamming, but bursting posts w/ obvious things that have already been said or don't make any sense so their manager thinks that's a good post. Since most managers only take a small glance at their post history - not checking the post context - they can't know for sure if that's a HQ post or not. So they assume it is.