Thanks. I understand now. It also explains why I was unable to reproduce the issue on my end (comments are disabled on my posts at the moment).

This case is indeed a bit similar to SkimLinks, with one big difference: Kissmetrics is only active for logged-in WordPress.com users, who consequently accepted WordPress.com’s Terms of Service and Privacy Policy when they signed up and who use their WordPress.com account to comment.

Readers visiting your site while being logged out won’t be tracked by Kissmetrics. Logged in WordPress.com users who opted out from Kissmetrics on WordPress.com also won’t be tracked.

If you don’t want to see the Kissmetrics tracker on your site, whether your readers are logged in to WordPress.com or not, you can leave Jetpack Comments deactivated. You will also want to avoid using the Likes Module.

In general, and if you don’t want to add any trackers that may be used by third-party services to your site, it’s best to avoid adding any iFrames to your posts or pages. iFrames load content that you do not entirely control.

If you look at my site for example, you’ll notice a few extra advertising trackers (Convivia and ScoreCard). I don’t use any ads on my site, but the trackers are added via the Vimeo and SoundCloud players I’ve added to some of my recent posts. That doesn’t mean that Vimeo or SoundCloud inject ads into my site, but that triggers the Ghostery warning.

In the case of Jetpack, both Jetpack Comments and Likes add iFrames to your posts. These iFrames load content from WordPress.com, and are consequently subject to the tests we run on WordPress.com. Kissmetrics allows use to count the number of Likes and the number of comments WordPress.com users make.

I hope this clarifies things a bit.