I recently flagged this answer as spam. While this answer is a little longer and more useful than many spam posts, I still flagged it as spam because it contains an undisclosed affiliation with the promoted material. For those of you who reviewed the flag, why did you decide to approve/deny it? I still firmly believe that this is spam but I am interested in hearing other opinions.
The undeletion is my mistake, I always forget that if spam flags get cleared on a post, it gets undeleted automatically, but it does not show as much on the screen unless I reload the page.
As for clearing the spam flags, the link got removed by the author, so I don't see why to keep the penalization on the account when there is a clear indication that it is not owned by a spammer.