Have you tried this one?

http://www.gog.com/forum/general/gogs_general_trading_thread/page1

not yet but ill have a look later on

I appreciate the sentiment in the OP but I feel that it is solving a problem that doesn't exist--or at least has been blown wildly out of proportion. I have traded dozens of games over the years and so far I have only be ripped off once. Perhaps my experience is an anomaly but the suggestions in the OP seems like trying to use a tank to kill a gnat. In the end so many hoops are not only going to stop the cons, it is likely to kill trading altogether by turning off legit traders.

Is there some API to validate a GOG key without activating it? If there is one it shouldn't be too difficult to set up an escrow service:

* Both participants enter the keys and the games they correspond to, but they don't yet have access to the traded key
* The escrow service verifies the keys against the specified games and shows the results to each counterparty for confirmation (to prevent someone entering a key for a different item). If both keys are valid and confirmed, access to the traded keys is granted simultaneously

If the API is not available to the public, maybe GOG can be persuaded to set up the escrow page (perhaps with a nominal charge if the trade is successful).

It isn't completely trivial, there are some challenges (e.g., protecting it from scriptbots doing fake trades and using the service to guess valid keys) but it should be reasonably easy and would limit the chances for scamming

Wpegg attempted this a couple of years ago. Similarly to this thread, the community at large couldn't be bothered.

Thanks for finding the link - was going bonkers trying to find it yesterday. I believe wpegg intends to reboot that site as well.

Starting a thread shouldnt mean you get special rights over it. Mods, you should not lock threads just because the OP wants it to end. There are other people using it, k?

A little something to make trades safer:

http://www.gog.com/forum/general/my_list_of_people_ive_successfully_traded_with