I've worked as a remote (U.S. based) independent freelancer through Elance and Odesk. I've had positive and negative experiences on both. They both do a decent

I've worked as a remote (U.S. based) independent freelancer through Elance and Odesk. I've had positive and negative experiences on both. They both do a decent job of minimizing the risk of non-payment on fixed-price projects, but, as you point out, one of the biggest challenges is nailing down the requirements. I understand that requirements can and will change but there have been times when I've spent an inordinate amount of time going back and forth with my point of contact (who often doesn't really know what the primary customer wants). There have been times when I've pulled the plug and just told the client we weren't a good fit. I've also learned when to recognize that the clients are looking for speed/volume vs. quality. I know there are often tradeoffs but some clients just really don't seem to care about quality; they are middlemen who just want to throw something over the fence to the client.