#It is spam
It is spam
This flag reason is pretty straight forward, with a few caveats. Spam is pretty easy to spot. Obviously purchasing Lucky brand jeans will not answer your questions about Ubuntu, if you see one of these posts use this flag reason instead of the "not an answer" flag reason.
The only caveat is with self-promotion. Self-promotion is allowed on the site to an extent. First the post must identify this is a solution they've created or work for, secondly they need to provide more than just a link (that is, either an abridged version of the solution, or a brief explanation of how to apply the software to fix the question asker's situation).