If you go to Google (only works in Google which I'll explain later) and search for sell gold the first organic result will be howtosellgoldforcash.com (I'm not going to give them another link). This site appears to be an independent review of some top online buyers of gold and jewelry. All of the main players are represented and there appear to be plenty of links to the various sites with reviews. But, if you look more closely, all of the links point back to howtosellgoldforcash.com except one--EmpireGoldBuyers.com.
Supposedly the person running the site has sent gold to all of these various places and the one that they had the best experience with was Empire. How convenient that this person also appears to be running either an affiliate site for Empire or is doing SEO for Empire (probably the "partner" they refer to on the site). Everything else on the site is used to build credibility of the "independent reviews" and funnel traffic back to Empire. Just about every review compares the company being reviewed to Empire so that another link to the Empire affiliate site can be tallied up.
This is also replicated across other sites targeted at additional keywords consumers are likely to use when selling gold, including "scam" related keywords.
Google gives a lot of weight to inbound links and ranks inbound links on quality factors like domain authority. Domain authority means a link from WhiteHouse.gov is worth a lot more than one from InternetPerformanceGroup.com (had to get a link for ourselves in there). Getting links from highly trafficked, authoritative sites is SEO gold--and extremely difficult to do. The next best thing is to create your own network of sites and generate your own links. This is precisely the tactic employed here. This is also why this tactic works well for Google, but not for the Yahoo/Bing combination.
The other reason this works well is because there is a lot of weight placed on the domain name for a site. It is very likely that if someone is looking for a specific website they will type the website name into their search engine. With the keyword focused domains and plenty of links an empire of SEO deliciousness occurs. (pun intended--it's Friday)
The type of scam outlined here is precisely what the FTC is cracking down on with the recent charges settled by Reverb. Truth in advertising principles require that paid endorsements be disclosed, including online. This means if someone is putting in a review of something, and they will be compensated in any way for the review, they need to disclose that they are a compensated endorser. Unfortunately, the Internet is still a little wild west when it comes to enforcement so it will be some time before we see widespread application of truth in advertising online.