-Rep A terrible experience.
We agreed to trade my Yakuza 0 x his The Escapist 2. I went first and then found out that his key is SA region-lock when I tried to activate it. He got Yakuza 0 for himself and I got a region-lock and exposed key without knowing whether it was/are/will be available. I tried to propose a replaced game from his list but he refused. He wanted me to use VPN but I didn't want to risk my Steam account.
In the past, I only cared if my games were region-locked. But I learnt my lesson to be careful with region-locked games from others before trading.
Full chat is here