Continuing with the Google confirmations we now have Google’s John Mueller stating that there are no Google algorithms that target user actions on your website. He further said, “I don’t think we even see what people are doing on your web site.” So comments, form submissions, and general user interactions don’t help your websites ranking.
So in general, I don’t think we even see what people are doing on your web site. If they are filling out forms or not, if they are converting and actually buying something… So if we can’t see that, then that is something we cannot take into account. So from my point of view, that is not something I’d really treat as a ranking factor.
The question came up during a Google Webmaster Central hangout, and can be found at the 38:11 minute mark in the video above.