I'm a moron - learning how to check for region-lock

So apparently Steam has gifts that are set to be region locked, and when you live in those countries, they don't put that helpful red '!' button on the top-left of the game to tell you that it's region locked.

I'm not blaming anyone, but exactly how do i check to see what regions can only redeem Steam gifts? (Not giveaways,mind you, but those gifts you find in Steam Inventory) Don't want this to happen again.