Google just launched a Manual Actions Viewer in new webmaster tool which enable the website verified owner to see if there is any manual spam action applied by Google Spam team or not. You can see the new Tab below the Search Traffic named as Manual Actions.
Google has documented different type of Google manual actions here. The below is the list along with links for your reference.
- Manual Actions
- Cloaking and/or sneaky redirects
- Hacked site
- Hidden text and/or keyword stuffing
- Pure spam
- Spammy freehosts
- Thin content with little or no added value
- Unnatural links from your site
- Unnatural links to your site
- Unnatural links to your site—impacts links
- User-generated spam
If you through the above 11 document content and videos you can find yourself the issue related to your site ranking.
Now Matt Cutts here