C12 Sorry I Missed

After Kasalina left, Elmer said to the robber hiding in the corner of the wall, "You are a decent robber. You should not pretend to be unconscious. It's not professional of you at all."

Hearing this, the robber broke out in cold sweat. Why was this guy so perceptive? Was he so incapable at pretending? The boy must only be guessing.

With this in mind