Maybe I am not thinking of all the complaints that would arise. The way I see it, is if you have an issue then just suggest a way to make something better. That's what this forum is for. If you have a complaint about a member, then report him/her.
Yes, I think this forum could be appropriate for complaints as well as suggestions, the only thing here is instead of having you give complaints, it is preferred that you suggest ways to fix it. You could say that "There are too many spam topics" but to make that a better thread, you could suggest that people read the Help sections, ask for help from moderators, etc. A complaint is really only half of what should be presented, if you have a complaint you should offer at least some semblance of a suggestion on how to fix it.
like she said this is the board for complaints. But if you feel a user is spamming or dis-obeying the rules to much I suggest contacting an admin/mod about your problem.
