This is why deposits and such are needed, I'll admit though...i'm a great client! Anyone who does work for me...should know that. I always pay well and more often than not will tip the designer/programmer for their services. However, i've had more problems with people working for me than clients. Enough is enough when you're more bothered about their design than they are. I would always ask for a 50% upfront deposit and measure progress along the way, if you think things are heading in the wrong direction then have a quiet word and try and get things back on track.