Your last flag was declined please review it before flagging this post

Question

I marked an answer on this question How to get a list of broken links using Powershell? for Sharepoint 2010 as a spam, because I thought that answer is more about letting user know about the product than answering a question. This was the first time I flagged any answer as a spam. But this flag was declined with below message

flagged as spam declined - a moderator reviewed your flag, but found no evidence to support it

May be I am not sound on the practice of flagging a post as spam.

I have 2 questions on this.

1. When I see that answer, its deleted now. Should I have flagged that answer not as spam but something else?
2. When I tried to flag another post I could see a warning in a pop-up(refer below screen shot). What does it indicate? Do I need to be careful while flagging?

Answer 1

I just saw an issue like this over on the Travel site, so I'll steal my own explanation from there:

For what it's worth, spam flags are intended for use on only the most egregious cases, like "ChEaP GUCC1 BAGS HERE" or "STREEM LIVE 5PORT5 |\|0VV!" They show up with priority in the mod queue and carry a hefty reputation penalty for post authors when enough accrue (just like offensive flags). The case you described is reaaaaaalllllly on the borderline... it's obvious why you considered it spam, but it's also at least intended to be relevant to the topic, so one could argue that it's not technically the intended target for spam flags. For more info, see the community FAQ on Meta SE.

Ultimately, though, only the mod who handled the flag could say for sure what happened. Could be a difference of opinion about that borderline case, or something as simple as a misclick in the mod menu.