How can you tell the difference between professional clients and amateurs?

I recently attended the RGD's DesignThinkers Conference in Toronto and met many smart designers running very successful businesses. One common denominator is that they all seem to understand that what you need are "professional" clients, not amateurs.
 
I wanted to get some feedback -- so I asked this question on the CFC Linkedin Group.

What are the qualities and characteristics of "professional" clients, besides the fact that they value your services and don't waste your time?

And here's what I found out:
 
Elle Steiner of MODA says, amateur clients "are the ones who pay less, complain more, and take more time than my 'professional' clients. There are often clues to indicate an 'amateur', but I find that when I don't under-sell myself, that is usually the best way to avoid this type of client."
 
Katie Calvert says, "I realize that I am working with an amateur when I become the "visual simulator" for my client's own ideas and thoughts. I've had clients who only seem to want me to do exactly what they have in their own head - I'm just there to catch their vision rather than give them a fresh and professional designer's approach."
 
What do you think? What are the characteristics of "professional" clients?

Comments

[Stan Faryna]

Regardless of who brings the vision, the professional designer's job is to solve a problem- artfully. Typically, that problem is a business problem such as make the message stand out. This requires some insight into the audience and what gets their attention. Not the client's attention. And not yours.

A great client knows that they want specific results and they are committed to support the process and people that will make results. Without results and accomplishments (yours or theirs), understanding how results are accomplished is always going to be messy.

The messy is what tires and frustrates you the most.

Stan Faryna

Feel free to connect with me on Twitter: @faryna
http://twitter.com/Faryna

[TurtleBlueBird]

Timely-ly enough, I was at a networking meeting this AM, and a high-end residental contractor talked about how a guy he had worked with taught him to consider the following 4 categories when meeting/working with a potential client/client:

Sophisticated in a good way
Sophisticated in a bad way
Unsophisticated in a good way
Unsophisticated in a bad way

It seemed like a great perspective on it. (Probably needless to say, he was urged especially to stay away from the "Unsophisticated in a bad way!")