From the comments: > here’s a strange little story that happened to me a while ago – I set up a gmail account to deal with nigerian letters and such (I wanted to collect some data to report the spammers/thieves, without compromising my actual e-mail address in the process). I set this up with a fake username (something like george.thompson or so) and a password which included the word “nigeria” in it. Lo and behold,…
He'd have to have a sterile browsing environment to ensure his ads weren't related to something else on Google's ad network.