Maybe I'm just thinking out loud, but it seems that for every great customer you find, there are a handful you are indifferent to, and a couple that can make your blood boil at the drop of a hat. The list of offenses is a mile long and could be anything from never giving specific feedback on disqualifications up to refusing to pay a fee. No matter what the transgression, recruiters still need to make placements to get paid, so when do you move a company from the 'client' to the 'source' category?
To be perfectly honest, I'm no longer in the position to do this myself since corporate recruiters don't exactly have the freedom to tell Mr. Manager they are no longer going to fill any of his positions. For us, even the worst of customers still needs to be serviced. However, for our friends in the search business, this isn't the case and a conversation with a friend got my wheels turning about just when enough is enough. This recruiter (working for a firm) was part of a team trying to build new business. One client in particular was a tough nut to crack and despite several close calls, 9 months after the first submittal there was still no hire activity.
It was then that my friend reached out to do some checkups on long-time candidates of his. One particular phone call resulted in the discovery that said company had proactively reached out to a candidate only a week after the 6 month ownership guarantee expired and offered an interview for the same position she was submitted to but the company claimed was canceled! Roughly a dozen phone calls later and it became clear what had happened - this company was using search firms to stock their talent pond! It goes without saying that ties were broken in this instance, but it isn't always so easy to tell when it is time to make the breakup call.
Now I'm not suggesting to turn every client who goes a couple months without hiring a candidate into a source, but it is also important to make sure you're not getting walked on. Even on the corporate side of things I'm a huge advocate of relationship building, but those relationships need to be mutually beneficial, especially in the search world.
I won't claim to be an expert, but for my money, the second a client is all take and no give, it is time for the 'come to Jesus' talk to take place. Keep in mind, there could be a very legitimate reason for the departure from the normally blissful union of supplier/customer. However, if the client cannot convince you that the intentions are nothing but good and the next time around will be different, it might be time to think about shifting your priorities elsewhere. After all, a customer that is stocking their pond with your candidates will never pay the bills, so why not work on strengthening your relationship with the one that does instead?