I find deciding what to do in these cases depends a bit on understanding where the client is coming from. Is the client genuinely making an effort, but is under some kind of limit of time, skill or whatever on their capability to get things done? Do they understand the value of what they're asking us to do for them, and demonstrate appreciation of it? Then we're often prepared to be more accommodating. Conversely, is the client apparently just willfully ignorant, entitled or lazy and feel they can spend our time like free water to get out of having to do their own part in the specification and production of their order to meet their own (often poorly stated, contradictory or shifting) goals? Then we're more likely going to revert to policy.
So yes, at our shop we do have a policy to charge for project preparation, support & consultations. It's an hourly rate, and that rate isn't all that cheap, especially if it involves one of our team principals. Our primary purpose is to produce great work for our clients; it's what our business is, and what we're primarily paid to do. I.e. our production fees go to the actual production of work. If a client wants to engage but isn't ready to have us start producing work, we're usually more than happy to assist them in various ways if they so wish. But since doing that takes skill, experience, resources & time, and all of that comes away from other clients who in fact are ready to have us produce their work, our default policy is to charge for the up-front assistance.
Of course like any good business, we may waive our own policy at any time, if we feel there's merit in doing so. We'll bend over backwards at minimal or no charge to help a client who has brought us repeated work over the years. We'll do a reasonable initial consult at no charge for a new client with a good-sized project, to establish our credentials and help both parties understand if it's a good match up. Or we'll assist a client who is up against a big deadline through little or no fault of their own; sometimes s*** happens and someone just needs a helping hand out of a jam.
Basically it's about value exchange. Both parties need to appreciate and value what the other is bringing to the business relationship. As long as we feel that's on track, with support fees as a possible part of that equation, we're cool to do what we have to do to produce the work. If the value isn't understood or appreciated, then regardless of the support fees it's probably not a business relationship that's going to work out.