Google has always maintained that paying for Google AdWords ads doesn’t have any effect on your organic search engine rankings. They just don’t share the same databases, so there’s no way for Google to know if you paid for AdWords ads and relay that information to the organic search team or its algorithm. I have to say that I agree with them–by mixing the two or allowing those two database to essentially “talk to each other”, there would be serious consequences and a lack of overall trust by the public in organic search.

As Google organic search begins to rely more on more “human factors” that are more and more measurable, it’s more likely that Google AdWords ads will come into play and start to have an effect on a site’s organic search engine rankings. For example, when a site starts seeing more visitors from paid search, users tend to initially come from paid search–but then they may go back later and perform some brand searches, which then affects organic search traffic. It’s those same visitors who may share the content and interact with it on the social media sites, which could then effect organic search traffic, as well. Then, finally, one theory I’m toying with is that Google is watching the overall traffic to a site and the level of engagement by humans. The more popular a web page, article, blog post, or site becomes, the better it will perform in organic search. As that traffic fades, so does the site’s organic search engine rankings.

So, when it comes to the correlation between Google AdWords and Google organic search, there may very well be a correlation between the two: but it’s traffic related, not because of the fact that Google AdWords and Google organic search shares the same database or the same data.

But let’s not forget a study that Google did back 2012, called Impact of Organic Ranking on Ad Click Incrementality:

There is a strong correlation between organic search and paid ads when you’re running paid ads. You get clicks on your organic search results. And, guess what? Google tracks the clicks on your organic search listings. The more people who click (and don’t pogostick back to the search results), the better your organic search engine rankings. Or at least Google’s tracking the clicks on organic search and using that data somehow in the organic search algorithm.

It’s not surprising to me that if you stop paying for AdWords ads your visibility in organic search will go down as well.

Recently, there have been some interesting reports and comments regarding eBay and the fact that Google has penalized the popular online auction website in organic search. eBay stopped paying for Google AdWords traffic about a year ago. As a result of not participating in Google AdWords, I can see how eBay’s traffic started going down over time, as they just as visible as they were previously. eBay was recently penalized in Google’s organic search results either by an algorithmic penalty–or with a manual action (or both). eBay nor Google is commenting on what the current situation is. But, nonetheless, it’s clear that the site’s traffic from organic search has gone down.

According to SEMrush.com, eBay has suffered significantly with this last Google organic search update:

A SearchMetrics report shows that eBay has suffered a 78 percent loss in search traffic.

According to SE Roundtable, conspiracy theories exist around the loss in eBay’s organic search traffic. Apparently there are theories out there that say that this some sort of backlash or penalty for stopping paying for Google AdWords ads. Reports say that eBay spent over a billion dollars in Google AdWords ads. And they’ve stopped advertising in Google AdWords.

Frankly, I personally believe that Google wouldn’t be so bold as to do something like penalize eBay for not paying for Google AdWords ads. They just wouldn’t do that, as it wouldn’t make sense: if it were to be connected in some way, there could be strong repercussions and most likely some sort of legal action would come as a result.

My theory is that Google AdWords ads, and the traffic that it generates, has an effect on a site’s organic search, especially given the fact that “human interaction” with your website is so much more a part of the Google organic search algorithm than it has been before. The fact that Google has been cracking down more and more on low quality, thin content with Google Panda is related. How much unique content really is on eBay? Many sellers upload literally thousands of listings, with all sorts of duplicate content, and that content doesn’t stick around for that long. It eventually goes away when the auction is completed. That has to come into play here.

There’s no evidence that Google has consciously dinged eBay because they stopped paying for AdWords ads. There never will be. But think about it: if you stop getting traffic to the site, there’s less human interaction with your site, people don’t search for your brand as much as they did in the past, and they don’t socialize your site as much as they used to. And that’s what’s going to effect organic search traffic.

Sure, there could also be a Google algorithmic or manual penalty on eBay’s site, as well. Does it really matter? I don’t really care at this point if eBay ranks for a keyword phrase or not: I’m going to straight to eBay to bid and buy. I’m not going there because I found something in Google organic search.

Bill Hartzer is Globe Runner’s Senior SEO Strategist. Connect with him on Google+ or on Twitter as Bhartzer.