Most sales literature and training focuses on techniques used in the acquisition of new clients. Sometimes salespeople sell their products to anybody at all and then try to keep each of their clients without critically assessing them in any way. But the truth is that occasionally there are clients who simply will not pay off, mostly due to the time you have to waste on them and the problems you need to solve because of them. How to detect customers that you would be better off without? Here are six typical signs of such problematic clients.