You can't trust a ladder. It will always let you down.

Behind the Groan

Let Down in Two Directions

To let someone down means to disappoint them, which makes the opening sound like a warning about an unreliable companion. A ladder can also bring a climber physically downward, giving the same phrase a literal job. Read the first sentence with serious suspicion. Keep the second sentence calm and certain, without emphasizing “down.” The straight delivery lets the emotional meaning arrive first and the ladder's vertical meaning follow a moment later.