Fire Difficult Clients?

the [non]billable hour bravely tackles the subject of whether or not to continue on with bad clients.

Here's the list of "fire-worthy" traits. Run the other way if you see them coming.

• THE DISILLUSIONED consistently expresses disappointment with your work even though it is of good quality and conforms to spec.
  
• THE SUSPICIOUS consistently expresses a lack of trust, disdain for your work, or questions your integrity.
  
• THE CHISELER consistently complains about your bill, even though it conforms to the estimate they agreed to.
  
• THE SOMETHING-FOR-NOTHING consistently increases the scope of the project but refuses to pay for the additional work.
  
• THE SLOW PAY consistently pays invoices late.
  
• THE MONEY PIT consistently is unprofitable.
  
• THE CLINGER consistently makes unreasonable demands regarding your availability.
  

This is not the full list - the original post can be found here.

Something to be learned from this.