Why not report those sites?
Reporting never works. Because competitor will report each other for some random reasons and that way tons of requests are piling up. I have never seen google taking action against those people.
There is new trick(called autoblogs) that thieves use to increase the garbage, using your (okay our) content. They copy our content and give linkback at the bottom or within content to save their backside from legal hassles. And using backlinks and other SEO they rank over you and google simply ditches you. This technique is called as autoblogs and with affiliate ads and CPM ads people are earning lots of bucks with it. Some are even copying software .exe and creating lots of subdomains to rank on google for the soft download.
Now before google write the blog post like that to announce their algorithm's inability to detect thieves, i think they need to work on beating this tactic from thieves before claiming - do this or that to combat spam. They're doing nothing as far as i can see on the example, i mentioned here.
One simple innovation would be to have a thumbs up and a thumbs down link in the search results page for each link so that rubbish can easily be reported*.
There is a way to get around this, if someone codes a bot to thumbs up their own site across multiple IP's ? Trust me, google can't even detect autblogs, let alone catch multiple IP's.
It really worries me when forums like blackhat this-or-that comes to crack google's algorithm in their favor and do succeed in that. We assume google is too powerful but in reality it's just another algorithm made by humans so there is going to be a pattern in a way humans think, so the flaws.