Have you seen the message that sometimes pops up in your WordPress posts: “About these ads”? You don’t see any ads, just the message, and when you click on it, the message just goes away.
Well, try this: log out of your blog and go incognito. (That’s what it’s called in Chrome.)
“Pages you view in incognito tabs won’t stick around in your browser’s history, cookie store, or search history after you’ve closed all of your incognito tabs.”
Now visit your blog. Do you see the ads? A moment ago, it was this one: