I should probably pay more attention to my own site.
While I was working on my blog last week, I noticed that there were advertisements showing up in the Related Content links at the bottom of all my posts. I was quite shocked as I never added them intentionally. I feared that my blog was hacked.
Digging just a little deeper, I quickly found the culprit: the Shareaholic plugin. I used it for related content and the social sharing buttons for the posts. It turns out a few months ago they sneakily added in monetization options in their plugin update without having blog owners explicitly opt-in. That means once you updated the plugin (if you’re using the WordPress panel to do this, there’s pretty much no changelog or notice), ad links would spontaneously spawn on your site. I guess if you’re a better blog owner you would have caught it sooner than I did. I understand developers need to make money too, and I’d understand forcing advertisements on the admin panel, but having advertisements enabled by default on the public site is a very sneaky process.
Needless to say, Shareaholic has since been removed from my site. If you’re still using Shareaholic, you should really review its settings to make sure it’s doing what you want it to do. For me, I’ve found other plugins to replace the functionality including Floating Social Bar and Contextual Related Posts.