An article by Seth Godin was an eye opener. Let me explain. We always say - if there are bad clients, fire them. The problem is, we never dive in deeper to define 'bad clients'. Then fanatics of customer service like me keep on harping on the proving the best service to my clients. In the process we forget that a select few clients are never satisfied, they keep on abusing you without even appreciating or acknowledging your efforts.
In the process, without even realizing, your 'good' clients suffer. They are good not because they don't complain but because they are reasonable, they are good users of your product, appreciate your efforts and so on.
Read Seth's blog - do your own analysis. How much effort is being consumed by those 'bad clients' and what is your ROI on servicing them?