Glenn Gabe shared on Google+ a message he received about a site he is working on for a client (I suspect) about issues with it on mobile. Here is a copy of the message:
Google systems have tested X pages from your site and found that 100% of them have critical mobile usability errors. The errors on these X pages severely affect how mobile users are able to experience your website. The pages will not be seen as mobile-friendly by Google Search, and will therefore be displayed and ranked appropriately for smartphone users.
That is Google saying, we are going to demote your site's rankings on mobile search because your site has major mobile usability issues.
Why didn't Google just say, "demote," why hint at it?
Glenn Gabe found the language to be "interesting" and I agree. Why can't Google be more direct about this?
Another WebmasterWorld thread gets into the confusion webmasters have around much of Google's messaging and help documents. Now, this isn't to say that Google isn't way better than they were a year or two ago, and it isn't to say they aren't working on making it even better - they are doing that. But there is confusion and this is one clear example of such.