Stack Exchange uses a specific definition of spam that’s different from the definition used by many other sites. It’s most concisely detailed in the flag dialog:
Exists only to promote a product or service, does not disclose the author’s affiliation.
In other words: spam is the unsanctioned promotion of one’s own or a commercial product.
There’s an FAQ post on the topic of what spam is on Meta Stack Exchange, if you’d like the full story.
That means this is spam:
Who are they who believe that reason to look into anything that writes Malegenix so poorly? Do you have to not appear adventurous? It is also rewarding when you discover a Malegenix. This can be sized to fit. They were a lot more active after this. I can express this touching on Malegenix. That is dirty. It seems very interesting. Isn’t this exactly the function of Malegenix today?
Visit here <spammy link>
(That’s a real post, by the way.)
This is also spam, if the blog belongs to the post’s author:
Visit this awesome blog (link) to find the answer!
However, this is not:
To fix your problem, you should foo your bar and pass your baz to quux.
I wrote about this in more detail on my blog (link).
That post discloses the fact that the blog is the author’s, so it’s okay.
This isn’t spam either:
delete me delete me delete me delete me delete me
If you come across something along those lines, it’s most likely self-vandalism, which is where a post’s author has removed a post’s content in an effort to delete it. That’s not something Stack Exchange allows, but it’s not spam.
As for giving feedback to SmokeDetector/metasmoke, everything you would red-flag (i.e. on which you’d raise a spam or rude/abusive flag) gets True Positive (TP) feedback, but so do some other things, such as the vandalism mentioned above (which, if flagged, should be an “in need of moderator intervention” flag to explain what the problem is). For more detail on giving feedback to SmokeDetector/metasmoke, we have a Feedback Guidance page.
As always, use your best judgment, and ask if you’re not sure.