The Argument from Fallacy
"Argument from fallacy" is the formal fallacy of analyzing an argument and inferring that, since it contains a fallacy, its conclusion must be false. It is also called argument to logic (argumentum ad logicam), fallacy fallacy, fallacists fallacy, and bad reasons fallacy. Fallacious arguments can arrive at true conclusions, so this is an informal fallacy of relevance.
Emphasis mine, via Argument from fallacy - Wikipedia, the free encyclopedia