Google, unquestionably the number one search engine in practice, is owned by the public now. More than ever, Google takes utmost care to offer highly relevant search results of high quality.
Mounting popularity of Google has made strict restrictions inevitable to prevent fraud things from happening. Google has laid out strict punishment for fraud activities; even your account may get terminated as a result.
If you are thinking of using Adsense, along with working out strategies to take full advantage of Adsense, you must take the initiative to know about Google’s rules and regulations and be prepared to adhere to that. Even without you wanting it, frauds may happen and you may get banned by Google.
So, it is better to be aware how frauds happen and take preventive steps to avoid them.
Hidden Texts: Your Ads should be free from hidden texts. The letters should not be deliberately too small to read, to make them rich with keyword content. Hidden texts will get the same punishment, as hidden links would do.
Page Cloaking: If your page contains things that the user will not see but may make them click on it, then you are doing Page Cloaking. Using bot sniffers or browsers to serve the bots of different pages that your visitor will not see is strictly prohibited by Google. Ensure that you are not doing that.
Multiple Submissions: You cannot, rather should not submit one URL of Adsense as two separate URLs. You should not submit multiple copies of your domain and web pages. Be sure that your domain is submitted just once to a search engine.
Link Farms: Given the fact that you cannot control your links in, Google does not expect that from you. But it certainly expects to watch what you link to. Google has an upper limit of 100 per page. Keep it at that and be free from being a Link Farm.
Page Rank For Sale: If you are considering trading your PR links with other sites, give it a second thought. You can sell ads and earn the link. But do not do it on the direct advertisement of your page rank. If you do you may be facing an account termination in near future.
Doorways: Pouring in keyword rich redirecting links into your page is considered similar to Page Cloaking. It is better to avoid this.
Multiple Domains-Same Content: You cannot fool the search engine by having same content for multiple domains. Search engines do check on IP addresses, registry dates and much more. So avoid having same content on different pages, sub domains never forward multiple domains to the same content.
Having read the above guidelines, you surely would have an insight into Adsense’s restrictions and would have known by this time what not to do to meddle with Adsense.