I walk into a store and ask the clerk: "Do you have any diet Dr Pepper?" The clerk answers, "We have regular Dr Pepper."
Searching for a description of this type of response, I've found a lot of material on question dodging. But in this case, the respondent doesn't intend to dodge the question or avoid answering it.
I repeat, this isn't question dodging, evasion, or obfuscation like a politician might engage in. In those cases, the politician doesn't want to answer the question, and knows he isn't answering the question.
In this case, the respondent knows the answer to the question, and thinks he is providing it sufficiently. In his mind, his response logically implies an answer to the question posed, but that logic is bad/does not follow.
I find this type of answer extremely annoying. Basically the respondent is implying an answer to my question and making me decode his response, when he could instead just answer my question directly. The problem with this type of response in general is that I would be expected to take future actions/make future decisions as if I have the information I requested, when I really don't.
Descriptions of this type of answer that I've found are "non-answer" and "non-response," but I was just wondering if there was an explicit name for this horrible communication tic.