[vibhavs]

Noobstories contains links posted from newly-created user accounts. The category is intended for moderation and tends to have more spam than others - the OP is asking you to flag spam articles on Noobstories to maintain the overall high-quality of HN.

[PCheese]

How does one "flag as spam"? I don't see any such links on either the article discussion page or the user page.

Example: http://news.ycombinator.com/item?id=1652503

[bbatsell]

You need to have a certain amount of karma to flag, but if I recall it's fairly low.

[sorbus]

It's around 50, I think.