Why are some Facebook page comments darker than others?

Question

I've just noticed, that some of the comments on my Facebook page have a darker background than the others and the X button is always showing.

Other users cannot see these comments, only page admins and the users themselves can. Why?

Answer 1

Found the answer:

https://www.facebook.com/help/?faq=212854178736287

Why are some comments on my Page appearing in grey?

To help display only the most valuable content on your Page, automatic spam filters mark comments that have been detected as spam. These comments will appear in grey to admins, but will not appear to the public. Please keep in mind that comments that include keywords you have added to the "Moderation Blacklist" will also appear in grey. You can learn more about the "Moderation Blacklist" here.

To unmark a comment as spam, locate the comment on your Page, move your cursor over the comment and click on the "X" that appears. You can then select the "Unmark as Spam" link.