Google has started sending a new manual action spam notification for "spammy structured markup", which is also known as rich snippet spam.
Google has recently set a bar higher for the sites that will be able to display rich snippets by dropping 15% of the rich snippets. The new manual action message sent by Google is:
Spammy structured markup
Markup on some pages on this site appears to use techniques such as marking up content that is invisible to users, marking up irrelevant or misleading content, and/or other manipulative behavior that violates Google’s Rich Snippet Quality guidelines.