No one actually knows how Google impose penalty on our website. There are a lot of rules and guidelines to follow in order to stay out of penalty from Google. Following 100% Google’s TOS also does not guarantee that you will not get the penalty. Sometimes, sites that are completely white hat and follow each Google TOS as their daily mantra still gets penalty. So, it is totally up to Google staff that reviews your site. Usually, Google’s staff will manually check your site’s information before giving any penalty. You might get highest level of crawl rate from Google if your site is under review. It is easy to get a site reviewed by Google. Just file a complaint of paid links, spamming, malware or any other related issue to Google Webmaster. This will lure Googlers to review your complaints and if it is legitimate, the site will be penalized.
There are several ways Google impose penalty on a site. First of all, the ranking drop from search results. Depending on the seriousness of the misconduct, the penalty can be anywhere between -10 to -1000 in ranking. Let’s say for example, if you are targeting a certain keyword to be ranked top 10 in Google. You have participated in paid links scheme with dofollow value to increase these ranking in Google. Someone has filed a complaint about you or Google have detected abnormal back linking on your profile. This will lead to mild penalties to your current ranking in your targeted keyword.
You are lucky, if the penalty value is -10 because your current ranking will be drop to 10 positions low. For example, if you are ranking #10 for that particular keyword, with -10 penalties, your new rank will be #20. You can still improve your current ranking from 20th place, but the highest you can get is 10th place because there is a cap of -10 positions to your site. Getting mild penalties like -15 or -20 will permanently destroy our hope to reach first page of Google. For heavy spamming, it may lead to -1000 ranking penalty which will eventually remove your site from listings. Google only shows top 1000 positions in their search results. This can be considered heavy penalty as you may not able to rank for those keywords anymore.
There is other type of penalty specifically meant for duplicate contents. If your site got indexed and ranked for any duplicate contents posted, then you are most likely will face this penalty. Your page could be sandboxed into secondary results. You need to go the end of search results by skipping through top 1000 search results. At the end, you need click “repeat the search with the omitted results included”. Most likely your site will appear here if there is any copied content penalty imposed. Usually, article marketing that post same content to hundreds or directories can lead to this penalty. You might also want to Premium Copyscape for articles posted on your blog from guest poster to avoid this kind of penalties. Premium Copyscape charges $10 to give 200 credits; each credit can be used to check 2,000 words length article for any duplicate issue.
Page rank penalty also takes place for some high value penalty. I have seen top websites with huge back links but not able to go further than PR3. Each step in page rank is exponential value. Even a drop from PR5 to PR3 considered as a high penalty. Page rank update takes place 3-4 time a year worldwide. Most websites including their internal pages will get PR updated each time the update takes place. If no one else is getting update except you which is also a PR drop, then it might be a PR penalty specially imposed to you by Google. Of course, we can’t really differentiate the page rank penalty if it takes place during global PR update period. But, this is the best guess we can do on PR penalty.
Having bad hosting service could also lead to penalties. Hosting services that failed to update their platform with good antivirus or malware programs can show warnings in search results. Some webmasters fails to update their cart or CMS platforms too. Using common ecommerce platforms like Zencart or CMS like wordpress will secure your SEO and give flexibility to provide the best platform for your website. In order to keep their platform the best in the market, frequent updates released with more bug fixes. Failing to update to newer version expose our site to vulnerable attacks from hackers in insert malicious codes in our site. This will make our website a risk to visit and Google notifies that in search results which results in drastic drop in traffic.