How to check
Re: How to check[ Edited ]
February 2012 - last edited February 2012
Google check the quality of each single click on your ad and if Google algorithm find someone has intentionally clicked on your ad you will get the moeny back in your credit. You can read more about Ad and traffic quality at Ad Traffic Quality Resourse Center. Getting leads depend on how well you optimize the your camapign and how good is your ad text and landing page. We can say how much relevant is your keywords, ad text and landing page. Kindly read the Tips for Success in order to optimize you campaign.
As per my knowlege you can't find the IP address of people as Google don't share the personal information of user. But you can exclude the IP addresses such as IP address of your office or home for campaign. In order to do this click on your Network Tab, at bottom of page you will see Manage IP address exclusion (advance) link click on it and enter the IP addresses you want to exclude.
Re: How to check
You cannot get the IP addresses from Google as Dinesh said above due to privacy policies. However, you can get in touch with your web server guys to check for the web logs and IP addresses hitting your website. In case you find some IPs suspicous (after getting in touch with your server guys), you can exclude those IPs using IP exclusion Tool.
Just a thought!
Re: How to check
Yes, you will have to look through your web logs to find this data. But don't look for the referrer, look for presence of the gclid value in the query string (assuming you have not disabled auto-tagging). Using referrer data to identify AdWords clicks is an unreliable method.
Best of Luck!