I tend to hear that remark quite often, but it doesn't cause me undue alarm - if they knew more, perhaps there would be no need for them to hire a professional?

Although my focus is different from yours (design as opposed to maintenance), I believe the response to this opening statement is the same - you need to draw them out and find out what motivated them to contact a professional in the first place. Many people are not able to adequately articulate what exactly they want yet know innately something is "not right" and that they need help to correct this situation.

Although not a maintenance gardener by trade, I do encounter countless maintenance issues during onsite consultations and inquire of the client specifically if they have maintenance issues regarding certain plants or situations that they would prefer not to have to deal with. Sometimes it is because the situation has gotten so out of hand they are overwhelmed by it and don't even know where to begin to approach it.

So no, my first instinct is not to run but with my experience, help them verbalize what the problem is. Many very rewarding client relationships have begun in just this way. Of course, if you've been in the business any lenght of time you can sense who the real flakes and potential problem clients might be and act accordingly, but I don't think just a nonspecific need for help is necessarily a reason to run for the hills.

I hear it a lot. All it means to me is that I have to read them to figure it out. You get them talking, look at what they have, how they decorate, are they earthy crunchy, start talking about some landscape things and they usually chime in with some info, and then do your thing.

These are usually the people handing you ten cut out pages from gardening magazines a week later.

Some people try to take the approach that you are supposed to be the expert, so you they want you to prove it. They just fail to realize that they are part of your site analysis just as much as where the sun and shade are. Sometimes it does not hurt to remind them of that. But, you make your other site analysis by observation, there is no reason that you can't get what the client wants through observation if you have been at it a while. After that, you still might decide to run away.

I might add that sometimes equally as scary, is the client who 'knows' what they want.

If you come up with what they want by observing above-listed clue areas, rather then asking them directly they may thing you are a genuis later.

If you ask directly and get nothing, as the OP is speaking of you have to improvise. You can't leave the client not thinking that you have something that they want to pay for, or you are out of work. One way or another, you have to do that or they are the ones running away.

Not that it matters, but I read the original post as saying that the client started right off with announcing that they didn't know what they wanted, before there had been much discussion.

The question was answered before it was asked. The result is the same.

Actually Ron B, the first thing they said was that they hated their shrubs.I was so shocked since I get my work from other gardeners so who was this anomaly I was talking to.I was getting ready to back out but I looked at the shrubs and on a Findhorn level they were hollering at me to help them.
They were yellowing,not growing well,were'nt being watered at all except for rain,and most were in the wrong environment.I turned,hung my head and decided to stay and hear more from the owner.She went into other rants and compliants.The home is for sale--this is the real reason I was there "To pretty up things"
This is a first for me,so I will help the plants if only for a couple of days,write out recommendations for further work needed for the new owners and move on.
Funny as I was leaving I noticed the beautiful perrenial bed right across the street and thought maybe that's where I may end up.

Ask them how they want to use the space. That is always my starting point.