Where are facebook comments saved if not on Facebook?

Hi.

I am testing facebook comments right now, I wanted to see what happens if the user is not logged in via facebook and if they are.

If the user is logged in via facebook, they can put a checkmark posting the comment to Facebook.

So in order to test I made a comment, and removed that checkmark.
The comment was shown on the site, not on Facebook, so far so good.

But as an administrator, I have not way of deleting such a comment. It does not show in the usual wordpress comment system, and only the user who posted the facebook comment can remove it.

So how do you handle trolls, and spam if you use the facebook comment system? I guess you can't or what?

Kind Regards

Henrik