Reading it it seems it mostly boils down to "good faith"; does Google believe that you're including markup in good faith, or does it believe that you're going too far and providing a different experience for the visitor (human) vs algorithm. And even then, there are use cases (they provide them as well) where it's necessary and beneficial to provide additional info for the algorithm.
This is something we wrote about back in 2013: http://www.confluentforms.com/2013/07/googles-microformatting-mixed-messages.html
- Search Engine RoundtableExecutive Editor, 2003 - present
- Search Engine LandNews Editor, 2009 - present
- RustyBrickCEO, 1994 - present
Barry Schwartz is Search Engine Land's News Editor and has covered search news for over five years. Barry also maintains the Search Engine Roundtable, his own search blog that tracks discussions at the most active search engine forums. As the host of Search Marketing Expo Israel and a speaker at many search marketing conferences, Barry is always on top of the most important topics in search. He also was the former News Editor at Search Engine Watch, hosts a weekly video cast named Search Buzz Recap and is a moderator at several popular search marketing forums.
Barry is often quoted in publications such as Forbes, Reuters, Wall Street Journal, New York Times, Bloomberg, News.com, Publish and more. With five years of writing about search marketing tips and how search engines work, Barry has been called the hardest working blogger in search. Barry maintains a personal blog named Cartoon Barry and can be followed on Twitter here.
Mr. Schwartz is the CEO of RustyBrick, a New York Web service firm specializing in customized online technology that helps companies decrease costs and increase sales. RustyBrick sells custom web software including advanced e-commerce, custom content management systems, social networking sites, CRM applications, custom web-based business software, iPhone applications and much more.
- Baruch CollegeMarketing Research, 1999 - 2002