- History Sniffing: How YouPorn Checks What Other Porn Sites You've Visited and Ad Networks Test The Quality of Their Data http://blogs.forbes.com/kashmirhill/2010/11/30/history-sniffing-how-youporn-checks-what-other-porn-sites-youve-visited-and-ad-networks-test-the-quality-of-their-data/ 4 comments technology