Note for moderators: some sites, including Stack Overflow, have more permissive, overriding guidance on the handling of these flags.
What makes something spam and when should I flag it?
A post should be marked as spam only if it promotes a product, service, or similar; and is unsolicited or lacks disclosure of affiliation.
Due to the way search engines work, this includes links. For example, an otherwise normal post that contains a link to a website only in a punctuation mark is still spam.
Unsolicited means that mentioning the product serves no purpose other than promotion. For example, if an answer mentions a software that may solve the asker’s problem or a question about web programming references a website as an example, this is not unsolicited (it may still be spam if there is an undisclosed affiliation).
Lacks disclosure of affiliation means that the author is clearly affiliated with the product but does not disclose their affiliation. Note that a simple “my” may suffice. However, the disclosure must happen in the post itself; the author’s username or profile do not count.
If an otherwise valid post contains an apparent spam link and especially if the bulk of the post is plagiarized from another post or from an off-site source, flag as spam (example). Do not try to salvage the post by removing the spammy content. If you're unsure, you can often find the original source with a Google search of its first sentence.
Be specifically cautious when judging posts falling into this category. Sometimes it may just be an innocent user leaving a signature trying to get some SEO. (Related)
It should not be marked as spam when:
The post contains no useful information, such as an answer that says “I don't have an idea how to solve your problem”. Flag as not an answer instead.
It contains only gibberish, such as “sdhsgfdhsfdshs”. Use the rude or abusive flag for these cases. See below.
What makes something rude or abusive and when should I flag it?
A post should be marked as rude or abusive (formerly known as offensive) if it contains hate speech, obscenities, abuse against people, or abuse of the community or system, i.e., a clear violation of the be-nice policy.
Abuse of the system or community is everything that is created with the intention to harm them. This includes posts by new users that contain no useful content at all – i.e. gibberish posts along the lines of:
As a rule of thumb, everything that would be out of place in polite discourse is rude or abusive.
If an otherwise valid post contains vulgar words as an expression of frustration, edit the bad part out instead of flagging the entire post as rude or abusive. If this results in an edit war or rollback war, flag for moderator attention.
Note that this is very different from handling an otherwise salvageable spam post.
Do not use this flag because:
A post criticizes somebody or something in a civil manner.
A post is a (civil) rant in disguise. If any part of the post can be salvaged, edit out the rant-y parts. If not, vote or flag to close as Opinion-based (for questions) or flag as not an answer (for answers).
Somebody appears to have posted nonsense due to an innocent mistake such as a copy-and-paste error.
How does the spam flag differ from the rude or abusive flag?
The exact definitions of these terms are given above and the distinction can help moderators handle these flags if the problem is not blatantly obvious.
(Note that if the spam or abuse is hidden, it may be necessary to elaborate this in a custom flag.)
Otherwise, the system does not differentiate between these flag types when counting the number of flags it has towards the thresholds to automatically downvote or delete. There are a couple unrelated cases where the system does differentiate between these flags:
Deleted answers with at least one helpful spam flag count towards automatic protection of a question. Answers with helpful rude or abusive flags, but no helpful spam flags, don't count.
If a post has a single validated "rude or abusive" flag, it won't be used as a review audit in the Triage and Low Quality Posts queues, to prevent NSFW posts from cropping up in those queues.
What effects do these flags have on a post?
Spam or rude or abusive flags ("red flags") receive an extremely high priority in the moderator flag queue and come with severe penalties:
- Each red flag, during its validity, carries an implicit downvote from the Community user, which does not affect the flagger’s reputation. This also limits the visibility of posts: on main sites, questions with a score of -4 or lower aren't shown on the front page (-8 on meta sites), and answers with a score of -3 are grayed out.
- Upon receiving six red flags, the post will be locked and deleted, and the author will lose 100 reputation. (Locking means that users with the moderator tools privilege (“10k users”) cannot edit or undelete it.)
- One red flag from a moderator has the same effect as six red flags from normal users.
- The contents of posts that were deleted and got at least one helpful red flag will be masked from 10k+ users: the content isn't shown on the post itself, but can be browsed to in the revision history.
- If a post with pending red flags is deleted for any reason, even if not automatically by the system in response to six red flags or one from a moderator, the red flags will be automatically marked helpful. This will trigger this mask when viewing the post, but this doesn't necessarily mean it was deleted for that reason.
- The post content is not masked to moderators, who see the post content on the post as it would otherwise be normally shown. Other users can install this user script if they don't want these masks.
- Questions that are deleted automatically by the system in response to six red flags, or one from a moderator, also receive more masking than normal deleted posts: the list of potentially related posts in the <10k 404 page won't be there, and the title is stripped from the URL to the post.
When are these flags removed?
You can retract spam and rude or abusive flags like all other flags. They also expire after four days if the thresholds aren't reached. (Previously, they expired after two days - source.)
Rolling back a post to a previous state will revert to the number of flags from that particular revision. This allows the author (or someone else with edit rights) to rollback a post to which someone else introduced spam, rude, or abusive content in a later revision.
Red flags can be cleared by moderators, whether active or already dismissed. This will cause the flags to be marked as disputed, even though they may have been marked helpful in the past. Since these flags carry heavy weight on the post and its author, a special mechanism is provided to clear borderline flags without penalizing anyone (declining the flag would penalize the flagger).
In addition, this is sometimes used to remove bad audits from the review queues, as helpful spam flags can cause the posts to become review audits. (While only posts that are actually deleted by the system in response to six spam flags are fed into the queues as known-spam audits, some spam is too subtle to expect reviewers to catch and can result in failed audits even if the reviewer is paying enough attention to ordinarily pass).