I'm increasingly thinking that the only solution may be to have a search index with human editorial control. As much as I think Google deserves scorn for how badly they have made the search experience on the web, we have to remember that they're fighting a battle against SEO and spam. It feels like they have mostly given up. Any automatic solution will always be an arms race where they will be one step behind. The only way to get ahead is to ensure that all content has to pass through human moderation before it can be included -- that's the only way I can think of to break the cat and mouse game dynamics at play here.
Google, Facebook and others will never do this because it's expensive. Their cost savings is our toxic waste.
So what does a viable solution look like? I'm not sure. Maybe a system with distributed, volunteer moderators like Wikipedia. It's not perfect, but that model has held up remarkably well over its lifespan and has seemed to mostly hold its own against increasingly sophisticated attacks.
