If the ads you see are found at the end of blog posts then provided you see this link small About These Ads link what you are seeing is WordPress.com generated advertising.
WordPress.com does not use text enhance or text link ads or pop-up ads or links in comments. If you are seeing those then that’s a browser-ad-on issue, or in some cases, it’s embedded into free games downloaded from the internet. See here: Bloggers: Beware of Adware.
Hi Timethief. I did see the ads displayed again and noticed a “?” mark next to the words “ads not displayed by this site”. I clicked on the “?” and it was malware, something called “Coupon Connection” which I was unaware I had installed as it was packaged with some other software I downloaded. I have since uninstalled it from my computer. I am very sorry.