[bamfly]

For sure. They threw in the towel around '08 or '09. The prior years of yo-yoing between front page results containing ~60% webspam and 0% webspam settled into a permanent 60%, and they evidently just heavily downranked and/or started ignoring low-traffic sites to keep it from growing to 100%.

Their shifting from text-only "ethical" ads to being a more-ordinary web ad service, and putting ads inline with results, roughly corresponds with that, IIRC, which probably isn't a coincidence. Your ad-"results" probably get more clicks if much of the rest of first result page is crap. Many of the webspammers probably funnel money to Google one way or another, now. It screwed up their incentives to keep fighting that battle, I'd guess, which is likely part of why they stopped putting so much effort into it.