My turn to apologise for not being entirely clear.

I fully expect the business users I talk with to know what they want. However, I do not expect them to know (or necessarily fully understand) what they're actually trying to achieve. Translating a user's wishlist into a design that recognises the underlying business processes is a skill in itself, and if users could do it, they'd quite possibly be in a different career.

Personally, I find my users are very open and quick to give me what they want. However, I usually have to burrow quite a bit to get to the underlying requirements, and as soon as I explain the way I'm thinking, they will like as not come back with "Oh, I didn't realise you could do that! Well, in that case....". At that point we enter round two where they're reconsidering their request in the light of more possibilities than they expected.

None of this is me giving up on end users, and nothing they're asking me is a trick question, but it does require me to think on my feet a great deal.