I will try harder to find the right place to report it.
It's still in beta, I felt that I they must have there hands full. Features like "report this player" are not yet functional. I hope that no one will fall prey to the rippers more than once.
I'm sure the TCGO mods are aware of the problem. They have added a warning on the news page and I'm sure that go along way towards fixing the problem. However, the bogus trades are still on the public trade offers with messages like "Quitting the game, free Yanmega" with one click you can trade your Yanmega for nothing. It seems pretty clear to me who the culprits are.