I'm not on the bing team. But I make quite good coin from a lot of sites, which by my own admission, should be deindexed; sites you would complain about, possibly even report.
The problem here really boils down to:
Targeted Niche sites
Google used to LOVE targeted niche sites. I could create a blog called brooktroutfishing.net or something, and get it ranking in no time. All I needed was a couple of articles of low quality unique content ($10 domain + $20 for 2000 words of unique content), a few links and blam! Adsence money would roll in. I'd maybe add a 'news' section with auto posted, scrapped content, so it would seem 'fresh'.
Now Google has wised up to this. Now, targeted niche sites are a lot less effective (not that they don't work). Large, 'authority' sites are now preferred.
So what do I have to do now to game the 'authority' preference? Simple. I buy an expiring domain. I then make it on a generic topic, like fishing. And I have sections for each type of fishing:
And blam! I play into the 'large authority site' preference Google now has.
The sad fact of the matter is; SERPs will always have low quality results as long as it is profitable to game the algorithms.
The only thing SEs can do is constantly 'tweak' what works, so that those who don't stay up to date (that is 99.9999% of all SEOs) fail. But they will never be able to fully get all the SERPs to be 'highly relevant'
And things will only get worse. Right now, most people who have money weren't born with computers. But wait until my generation grows old. We will ALL spend our money online. And there will be more reason than ever for people to want to game the SERPs.