Our studies have shown that the any of the following signals are enough to get your site functionally removed from family safe searches (anywhere from a -8 to -500 penalty, or even banned – the more that’s wrong, the higher the penalty). Avoid these at all costs.
Manually reviewed OR algorithmically detected to be “spam”, “malicious”, “fraudulent”, “porn” (when not trying to be an adult related site) or “Useless / Off-Topic”
Any of these results after a review (either manual or algorithmic) will functionally drop your site from the SERPs. This applies to your onpage content and even your offpage content (i.e., your backlinks). Make sure your site has not been hacked and malicious, illegal, or adult content is not stored on your site (or mentioned in your backlinking sources).
LINK SPAM: +30% of Backlinks are from Banned, Penalized, or Flagged pages
Our studies have shown that as little as 30% banned or penalized pages linking to you is enough to warrant a penalty (this includes adult related content linking to you when you are not an adult related site).
Backlink Anchor Text Too Exact: +60% Exact Match Anchor Text
Our studies indicate that as little as 60% duplication in the anchor text of your backlinks is enough to grant a link based penalty, perhaps even less.
Duplicate Text Content Over 60%
Duplication over 60% of any other indexed page online (whether or not you are the originator) is sufficient to get that page removed from the index as a duplicate, either by Panda, or the standard PageRank algorithm.
Average Time on Site < 10 Seconds
If the average user spends less than 10 seconds on your site and then leaves (either bounces back to SERP, or closes the browser), then this site may have a difficult time surviving the Panda algorithm for quality.
Bounce Rate Above 80%: Index to SERP or Sitewide average
Our studies into sites hit by Panda indicate that if any site has a bounce rate higher than 80% they may have a hard time getting past the Panda quality algorithm.
Technical Onpage Spam: Keyword Stuffing, Hidden Text, Doorway pages, Sneaky Redirections, Cloaking (presenting one page to spiders and another to users), etc.
Trying to fool the algorithm (or a manual reviewer) with technical onpage SEO tricks is getting exceedingly difficult. The Google Rater’s document has an entire section devoted to these tactics, and they have special software to catch it. Trying any of these tactics is almost certain to get your site strongly penalized.
Slow Site: Site response time is more than 10 seconds on average
Studies show that site response time over 5-10 seconds can adversely affect your rankings. Check Google Webmaster Tools for any ongoing errors. Correct immediately.
Site / Page 404’s too regularly
If your site or page is returning a 404 code too regularly, or failing to load for whatever reason too much (perhaps 2 or 3 times), it will eventually be dropped from the index. Check Google Webmaster Tools for errors.
Information provided by SellHealth