Supreme Commander Keys are considered exploited, and cannot be traded, as per the site rules: http://www.steamtrades.com/trade/gCrkO/steamtrades-site-rules You're probably getting banned.
http://www.steamtrades.com/trade/search/commander
They usually don't get banned.
Well, do what you want.
But what is the point of bumping 2-3 weeks old threads (some of them were bumped about 2 days ago by a guy, but the creators are not active in them). It only gets real offers down faster. You could post links to their threads in reporting thread or something.
They site admins need to start taking more of an active stand against people trading exploited keys.
Thats why I think you should post in one of the sticky-s. Admins won't check all of the threads just because you posted in them.
Also, some people got these keys legit way (without proxy, multiple farming accounts) and some bought them on Amazon (and lost their money, because the game was free on that forum).
i have few Supreme Commander+Supreme Commander: Forged Alliance (steam key) for DOTA 2 (tradable).