Do you ask the cookies for google adwords? When somebody click a advertisment, then google will place a cookie in this computer. If somebody visit the point website. Then google will find if the cookie is exist. If it is exist, google adwords will add a transformation.
I use the hosts file to block all ads. Very nice and quite simple, just copy this text file and open the notepad as administrator then navigate to windows/system32/drivers/etc change the file type from .txt to all and open hosts -- paste the big list in and save. No more ads.