In "Confessions of an Agency CEO" we find some interesting questions about the nature of client relationships and whether that "good" vs. bad dynamic is associated with good work. I quote the passage I find most interesting below.
The Lesson is similar to the Zappos example: in a well-run company, culture often trumps strategy.
It’s often said that clients get the work they deserve. What separates
  the truly good ones from the awful?
  I am big believer that, whether they want to admit it  or not, agencies are defined by their clients. A client’s willingness or  desire to do interesting or innovative work is what’s going to help you  or hurt you in your attempt to create successful campaigns, build a  portfolio, win awards and recruit new talent. The client’s culture  invariably rubs off on the agency. It’s important to consider this going  in to any new relationship. Good clients are secure and accountable  individuals, who know what they need to do and can give clear direction.  They stand behind their word and defend their position. They don’t hang  the agency out to dry at the first sign of trouble. Good clients are  secure enough to take risks and are not afraid of being wrong. They  trust the agency and can effectively manage from a distance, which  allows the agency to focus on delivering a great product, not managing  an erratic client. Bad clients, conversely, are insecure, political and  weak. They are afraid to stand up to their peers and bosses. They try to  make everyone happy and get incremental credit along the way. Making  great ads is secondary to their petty need for constant validation.  Their insecurity and weakness leads to fear. And the fear leads to  constantly second-guessing their decisions.