I'd say claiming that your forum is the best in it's genre, for example if you had a promotion forum and you claimed it was "The best promotion resource" or something like that I automatically wouldn't go to it because it lied to me.
I wouldn't see this as a "no-no". You assume there are different members on each forum, so having the same message won't harm anyone. Then again, I see too many forum interlinked somehow by one bigger forum, so the members are the same, so that's why having the same message may be bad.
I'm not sure if this would be a promotion no-no, but it is silly to promote your forum on a brand new board, only because it doesn't have the member base that will see that "ad" and visit your link...
> PMing people to join your site: This to me is one of the biggest errors you can make if you want to gain respectability. Appart from the fact its usually against the rules most people don't like being bugged to join a site that's usually hardly developed.
> Promotion your site when you're not fully completed the set up and design. This always turns people off.
> Hijacking other people's advertising topics with your site link.
Advertising your site on one or more promotion boards to entice members to join the site, but the admin makes the forum, but hardly is ever there and/or hardly ever maintains it.
In doing so you may find spam posts, or people in the help section asking questions with no responce, giving feedback with no results, etc.
This just shows lack on the admins part. If your going to make a forum, you have to be committed to it. Comittment in my mind is being on the forum for at least 5min a day each day to handle any admin or other tasks.
If needed you could hire global moderators, or moderators, but now I'm getting beyond the scope of this threads topic.