Distinguishing NTLs by their syntax or semantics won't yield ethically useful conclusions for a utility maximizer because semantics and syntax, categorically conceived, lack any direct relationship to the NTL's consequences. You need a pragmatic standard; the common-law standard for fraud is a good starting point. For an act to count as fraud, the deceiver must intend to deceive and the deceived must reasonably rely on the false information. If the doctor tells the patient the saline solution is his most powerful sedative, would a reasonable person be justified in assuming the solution is a sedative, or would a reasonable person necessarily ask what the substance is? The answer, of course, depends on making the "reasonable person" more precise, but, if that's the kind of inquiry that's ethically appropriate, it points to the importance of preserving the patient's autonomy, even when deceiving him, and it speaks for some NTLs as better than lies. Some NTLs serve to maximize the patient's autonomy by allowing him to be unreasonable if he chooses and cooperate with his own deceit, while not foreclosing further inquiry if the patient really wants the truth. From this standpoint, I think "Don't distract me" is a more deleterious deception. The doctor silences the patient and ignores the possibility that the patient may choose to be informed, rather than comfortable. An outright lie that isn't credible could serve the same purpose and obtain the same ethical evaluation, except for the difficulty in manufacturing a suitable lie.