I just cannot appreciate a developer using such a site, while a sizeable portion of developers also work on very similar premises compared with designers; hourly payment and no spec work. (i.e. we'll buy your application if we like it.) For some people, mostly executives and other business oriented disciplines, this is a fair deal as it is what the free market bears; they do not and will not care about long-term health of the industry, the other side of the stick, or the designer on the line. It just doesn’t click for them, and that’s understandable somewhat because they’ve never been in a similar situation before.
But a developer using this service knows exactly what this entails, they are aware of the concept of spec-work, and maybe even had to do it for some reason. My problem is not the amount of money per-se, but with doing work for nothing, hoping that it will pay in the future. A developer cannot claim ignorance. It’s just plain nonchalant lack of empathy.