A few words from the FAQ (which I strongly recommend all of us read in its entirety!):
If You See a Problem, Flag It
Moderators have special authority; they are responsible for this forum. But so are you. With your help, moderators can be community facilitators, not just janitors or police.
When you see bad behavior, don’t reply. It encourages the bad behavior by acknowledging it, consumes your energy, and wastes everyone’s time. Just flag it. If enough flags accrue, action will be taken, either automatically or by moderator intervention.
So...if you see a post that you believe is a problem - that violates our common expectations about how we should behave - just flag that post. Flagging it will bring it to the attention of the moderators - and if a use accumulates too many flags, the board will automatially address the problem.