In many situations it is often useful to be able to say or write lengthy communications which purposely don't address a specific aspect. This is a classical situations for politicians which when asked a question will in fact provide a lengthy answer (which stops another question being asked) with very little being said in reply to the initial question. Another example is when a salesperson is asked for a price and he doesn't want to give it directly. Whenever it is required to occult a given information this can be achieved by saying something else instead, as long as people aren't too regarding, this usually works.
There are many techniques which are classically in the field rhetoric. See relevant KCards for the techniques of rhetoric which are particularly adapted to this, for example topics.
Here we develop an additional simple technique to the ones of rhetoric. It is called useless details because it consists in giving details about unimportant things while staying very vague about most important things. This technique works well, because the details you will give aren't irrelevant but simply aren't the ones the person really wants. The idea is to consider the subject you're meant to talk about and consider things which are clearly and naturally related. In fact, when asked a question many of such elements are often in the question, or very close to the question.
For example if someone asks you how much your product costs you can provide details about the product, the competitors, the companies overall pricing policies, the company and so on. All these elements are useless details and at the end the person will feel uncomfortable to repeat is request because it makes him look like he lost attention and missed the answer. If he does ask again, you can usually just repeat the same reply again.
This technique works particularly well in written communication as you can bury the very little important information you're willing to give in a pile of unimportant information you can give. This obfuscates the fact that very little is said about what is important as people get knocked out by the useless detail. This can go quite far, with a bit of habit, you can write 10 pages about a product without giving any details on the product's characteristics.