Earlier quoted context omitted.
I would attribute to malice things like active attempts to destroy the very forum - spamming is a form of "malice of the commons". You will know when you encounter malice because nothing will de-malice the poster. But if it is not malice; you can even take what they said and rewrite it for them in a way that would pass muster. In debate this is called steelmanning - and it's a very powerful persuasion method.
Spamming is an attempt to promote something. Destroying the forum is a side effect. It's fair to describe indifference to negative effects of one's behavior as malicious, and it is, indeed almost never possible to transform a spammer into a productive member of a community.
If you wanted to divide it further I guess you could discuss "in-group spamming" and "out-group spamming" where almost all of the promotional stuff falls in the second but there are still some in the first group.