As someone once put it, at the time you defend your dissertation (at least in science/math/engineering), you should be the world's greatest expert on your dissertation topic. If you don't know it cold, you don't deserve the degree. (Of course, that lasts only a year or so. Once your work gets into the literature, others build on it, and you have to run to keep up.)
Of course he worked only in the soft sciences and the humanities, not in anything rigorous. However, I had to wonder how his clients got past the examining committee, if they weren’t intimately familiar with everything that went into the dissertation.
This makes me so sad. I have learned the most about the field that I want to specialize in from various papers/projects before dissertation writing. These students are missing many learning opportunities by not doing these assignments. I mourn for the future of our society if this will be viewed as an acceptable practice.
P.S. Is this about http://www.writemypapers.org/ or http://www.usessay.com/. Seems like testimonials are from the second source.