Doing Adwords does NOT directly help or effect rankings. Integrity in this area is a cornerstone of Google’s business. If this were violated it would damage Google beyond repair, not to mention a slew of legal actions. Google would never risk those consequences. Google has stated over and over that Adwords advertising will not affect rankings. I don’t always believe Google but….
I have been managing Adwords and doing search engine optimization for my clients for many years. I have managed every combination of clients that do or don’t do AdWords combined with SEO. There have also been cases where SEO clients stop doing AdWords, or start doing AdWords. I can say that I have never seen anything that indicated that Adwords affected rankings.
There are a number of reputable SEO research firms that study this issue and every one of them has come to the same conclusion: Adwords does not affect rankings.
However, there may be some indirect effects to consider:
First of all, any visitor to your site can potentially help your marketing, they can like your facebook, follow you on twitter, subscribe to your blog, reprint an article (with a link back to your site), bookmark or link to your Infographics, share a page or image on a social media site. All of these can help your rankings, so getting more traffic from AdWords increases that opportunity.
Secondly, Google is looking at engagement metrics such as click through, time on site, page per visit, bounce rate –I believe that improving any or all of these engagement metrics can help your rankings, because Google wants to send visitors to sites that are engaging, entertaining and informative. With Adwords, you can be more selective on the type of traffic you drive to your site. It stands to reason that higher quality traffic should result in better engagement.
Thirdly, studies have been done showing that organic search listings have a higher percentage click through rate when an AdWords ad of that website is seen near the listing. The more times that a searcher sees your website listing (organic or paid) the stronger impression that is made..
Would I ever advocate using Adwords (even indirectly) to a client as a way to help with an SEO strategy? Absolutely NOT. There are many good reasons that one might do AdWords; getting more leads or sales and brand awareness are some legitimate reasons. Improving your organic position is not a good reason to do AdWords.