Seems like he has a couple of flag words "cheap and fast" in his URL that others have used in the past as indicators of spam domains, at least I've seen that for email. Even good isn't great to use.
And looking at the page naming conventions that carries all the way through. A broad brush penalty to over generalized key words indicative of spam, and shopping site type directories would definitely account for this thing getting crushed.
Unfortunately it seems like he's the one person out there making a site like this honestly and over optimized for a search algorithm that was inevitably going to change. Building a brand and using a more personal voice instead of thinking you can win at SEO is always going to be the way to go.