An interesting thread on WebmasterWorld forums discusses ways to diagnose a possible Google penalty. If you suspect your site / URL is being filtered out / penalized (e.g. you have lost some Google rankings), try doing the following:
- Dig your internal traffic analytics for traffic drops or bad trends;
- Perform [site:yoursite.com] search in Google to see if Google reports same number of indexed URLs;
- Check if Google Webmaster Tools report any problems;
- Take a look if Google toolbar PR has changed (graybar PR might be a signal of penalty);
- Check your site ranking for a “domain-name” search (without the TLD).
- Check if Google has blacklisted your site as unsafe for browsing (type http://www.google.com/safebrowsing/diagnostic?site=mysite.com with your domain at the end).
- Check the source code for any injected links to obvious “bad neighborhood” sites;
- Check your other sites. In some cases Google seems to devalue the WHOIS domain owner and this results in a simultaneous ranking drop in several sites under the same domain account.
- Copy a long phrase from your page and search Google for the exact match – make sure this very page (not the home page, not other sites scraping yours) is ranked #1;
- Check if your URL can only be seen by adding &filter=0 to the search URL – or clicking on the “show omitted results” link (this means you were hit by the duplicate content penalty);
- Any other? Please share your way to diagnose a penalty.
If such a query puts you in the fifties, it’s almost (!) guaranteed to be a penalty.
Further reading on dealing with penalties:
- 4 Google Penalty Flags : Have You Been Penalized by Google?
- How Many Google Penalties Are There?
- Google Penalties : Manual vs Algorithmic
And here’s a quick video featuring Google search quality team members explaining how to deal with the penalty without going into extremes