Google Adsense has been serving relevant and quality ads since a long time. The ads come from Google Adwords which is Google’s main advertising product and source of revenue. The advertisers are very important to Google so they are very strict when it comes to taking action against invalid click activity. This is one of the reason why hundreds of publishers loose their adsense account daily, If you are using ad sense you have to protect your account and report any invalid click activity noticed. If not reported immediately Google will consider those clicks intentional resulting a permanent ban.
How to Report invalid clicks:
Reporting invalid clicks is a simple procedure and is done by filling a Invalid Clicks Contact Form online in the Adsense Customer Support. section.
You have to enter your account details, the location where the code appears, describe why you believe the activity is invalid and provide information like IP address or traffic logs if any.
Tip: If you are using WordPress you may use plugins like Ad Logger, Firestats, Statpress, to track IP address in real-time. Alternately, you can use services like Statcounter, Sitemeter to track IP information of visitors.
Tips to protect your account:
1. Since your website is open for all visitors, anyone can mess with your ads by clicking numerous times (Click-bombing). It is advisable to check your adsense Reports daily and report suspicious activities.
2. Keep an eye on the CTR, if you find it unusual eg: from avg 2-4% to 20-30%. Inform Adsense team about it to avoid ban.
3. If you are experiencing unusual activity or bombing for 2-3 days or more, Best way to keep your account safe is to REMOVE all the ad units temporarily.
4. Avoid disclosing exact Page CTR, CPC, Page eCPM/RPM and revenue generated through each add unit on websites, forums, chat, etc…
5. Do not place ad units on pages with no content (blank or just images).
6. Do not use more than 3 ad links and 3 ad units on a single page.
7. Do not encourage others to click ads or use deceptive implementation methods to obtain clicks.
8. Do not modify the code, use only the code generated through Google Adsense (or if you are using the DFP Ad Manager). Any changes made within the code will lead to ban.
9. Do not insert ads in pop up’s, if any.
10. Do not use ads on Autoblogs or sites with prohibited content.
11. If you are using ads under Top Navigation bar with drop down menus make sure the sub menu/category NOT overlapping the ads as it may lead to ban. Advisable to use ads there only if you DO NOT have any drop-down list.
These are few very basic tips and common mistakes publishers do unknowingly.
To be on a much safer side go through Google Adsense Program Policies Page and make sure you in compliance with their policies.