Someone asked me to carry a bag into Korea. I didn't know there were drugs inside. Will I be believed?

Lack of knowledge is a valid defense, but courts examine it closely. They look at whether you were paid unusually well, whether the trip made sense, who arranged it, and what your messages show. If the circumstances suggest you should have suspected, the court may find you accepted the risk. The defense must be built on evidence, not simply on the words "I didn't know."