At some point you will decide that the majority or entirety of the fault for a false interpretation belongs to the listener. Then it all comes down to intent, which will make the consequentialists among us rather nervous.

If Sam expresses themselves in such a way that the most likely interpretation of their expression is A, in a situation where Sam knows that NOT A, Sam is doing something which is expected to result in their audience believing a falsehood. Presumably that's what a consequentialist cares about. No nervousness required, and intent is relevant only insofar as it influences actual behavior.

Whether we call what Sam is doing a "lie" or not, and whether we decide Sam is a bad person or not, is an entirely different question.

I agree with you about the differential reliability of an outright liar and a NTL-er, though.