Back then (and with "Remove result" and SearchWiki) it had issues because we were trying to get people to recognize spam, and people weren't that good at recognizing spam techniques like hidden text. The more recent complaints we've had are more like "here's content I don't like." So maybe it's time that we tried something similar again.
People are pretty good at recognising "scams", but you need to tell them that's what they're looking for, not just how the content makes them feel. It seems like the report spam button was a large factor behind gmail's spam filtering success. Would love to see the same approach applied here. I know I'd be hitting my report spam button in chrome pretty often :)
I just know I see a lot of worthless junky sites on the first page, and I wouldn't think it would be hard to recognize them using ML techniques, which requires training data.
Recognizing that not all users are created equal is (IMHO) an incredibly powerful insight that Google and many other companies overlook. Qualified, technically literate users will be happy to volunteer, but you have to ask.
I think the cases that Google breaks is that some people figure out some trick/technique that lets them become a small power circle, which they then obviously abuse. When Google works it's because they're able to algorithmically spread the power around and at scale see what is quality and what isn't. Therefore I think the better strategy isn't to concentrate power even within an "elite" class, in fact it's the complete opposite, it should be how to make sure the power is spread within the masses quite evenly.
I wonder if a change towards "human input" might improve things more.
For example, what if the Chrome browser had a big feedback button so that if users wanted to help improve the Google search results they could rate the usefulness of the link they just followed?