(The question will be found at the end, Question.)
As a user of any Stack Exchange's community, you most likely stumbled through a post where for you that would be considered spam, but you're not quite sure how to proceed, because different communities / users have different expectations to what spam really is.
Let's take as example / inspiration two situations I've encountered recently (this doesn't mean the answer to this question is solely based in them).
On Project Management, when reading a user's answer, I found another answer that has a "See Also" section at the end, including many links to other answers from the same user inside of the community, without disclosing the affiliation.
I created a question in Meta Project Management, explained the situation and still don't know how to proceed. From tripleee's comment, I've noticed a specific approach to spam (which I didn't read anywhere in the documentation):
Links within the same site are IMHO unproblematic. Trying to drive traffic to an external site is what the disclosure requirement is supposed to discourage.
On Stack Overflow, when reading about converting CSV to SQL, I found a post from a user mentioning a specific tool and linking to an external site. There was no doubt the user was the creator of the tool.
After analyzing the Q&As where the tool was mentioned, noticed five (out of 25) was from the same user (creator of the tool) and at least two from team member(s). From all the seven answers, only one of the team member(s)'s posts disclosed the affiliation.
I flagged as spam (all but one), explaining in the comments why I've done that. The flag was accepted for the user creator of the tool, which then edited the answers to include
(Disclaimer: I help run the tool)
(I am not sure how acceptable such edits are though, but this would be a different question.)
The other still awaits validation.
I would like to understand when we should flag a post as spam and when not, considering what was mentioned by tripleee:
lack of disclosure where disclosure is required VS voluntary disclosure where none is strictly required.
Note: I know of two good questions including similar information, namely: