If you use the tool to report a post/thread to the moderators, please fill in the comment explaining what you think is wrong with the post. If another moderator already dealt with it, the post has been deleted, or the reason for it being a problematic post isn't obvious then this makes the reported post very hard to deal with.
I don't know about other moderators, but I tend to ignore reported posts when the reporting user does not add a comment explaining what the problem is.