Originally Posted by
villox
Exactly. The entire point of these bags, even before this, is to be tamper-evident. No way they would hand one out empty, since it would allow you to tamper to your heart's content.
I think there is no art to this - recently I purchased good from duty free at AMS and went through security and they confirmed that my purchase was sealed and was ok. Not sure one can just put liquid in a regular duty free bag and pass security.