Official Google Webmaster Central Blog: Options for retailers to control how their crawled product information appears on Google...While the processes above are the best way to ensure that product information will appear in this Search experience, Google may also include content that has not been marked up using schema.org or submitted through Merchant Center when the content has been crawled and is related to retail. Google does this to ensure that users see a wide variety of products from a broad group of retailers when they search for information on Google.
While we believe that this approach positively benefits the retail ecosystem, we recognize that some retailers may prefer to control how their product information appears in this experience. This can be done by using existing mechanisms for Google Search, as covered below....
Not sure why you would want to use the listed options??? If you run your own retail ecommerce site be careful. From my experience, ecommerce software header coding is usually sitewide unless you know how to make it specific to a specific page. e.g. people putting the Google verification coding in the page header coding when you only need it on the home page.
