If the players have read the books or have any experience with fae in the past, they expect that everything the fae say will be misleading at best, and a lie by omission at worst. Managing expectations before the conversation may head off unwanted questions before they are asked.
If you're personally not that good at making misleading and opaque statements, answering a question with a question is frequently a good tactic. If the PC asks a straight-up question, you might respond with, "Why do you want to know that?" or "What good can come of this course of action?" A non-sequitur or change of subject is always good. A simple smile or frown or scowl may also do. Or they can simply up and leave.
If the PC demands answers, the response can become hostile, threatening or seductive, the flavor of which will depend on the personality of the fae: "How rude of a mortal to make such demands on your betters." Or, "This will not end well for you." Or, "Perhaps our time would be better spent in conjugation rather than conversation."
If you always keep conversations with fae vague and evasive, and never offer definitive answers or statements, players will soon expect they will lead nowhere. Which means that they will always suspect anything they're told, even when it's the bald-faced truth.
Which is exactly what you want.