A Christmas Carol is such a fool-proof story you can’t louse it up.

Maltin’s remark treats Dickens’s A Christmas Carol as a narrative with unusually resilient “engineering”: its moral arc (hard-hearted miser confronted by past, present, and future, then redeemed through generosity) is so clear and emotionally satisfying that even mediocre adaptations tend to land with audiences. Calling it “fool-proof” also nods to the story’s cultural saturation—viewers already know the beats, so filmmakers can vary tone, setting, or style without losing the core effect. The blunt phrase “you can’t louse it up” is partly comic emphasis, but it also implies a critical standard: if an adaptation fails, the fault lies with the production, not with Dickens’s underlying structure.