I have never left a Facebook comment on a third party site.

Partially this is due to inconvenience, (the web browser with my Facebook login credentials has always had its own VM, to prevent like button tracking) and partially because associating my real name and identity with a blog comment seems like using a cannon to kill a squirrel. If Samuel Bierwagen wants to say something about an issue, he'll write an essay about it; but rolling out my name and my face for a TechCrunch comment just ain't going to happen.