If you haven't, you should check out The Shadow Scholar, The man who writes your students' papers tells his story. This is the conclusion:
"Thanx u so much for the chapter is going very good the porfesser likes it but wants the folloing suggestions please what do you thing?: "'The hypothesis is interesting but I'd like to see it a bit more focused. Choose a specific connection and try to prove it.' "What shoudwe say?" This happens a lot. I get paid per assignment. But with longer papers, the student starts to think of me as a personal educational counselor. She paid me to write a one-page response to her professor, and then she paid me to revise her paper. I completed each of these assignments, sustaining the voice that the student had established and maintaining the front of competence from some invisible location far beneath the ivory tower. The 75-page paper on business ethics ultimately expanded into a 160-page graduate thesis, every word of which was written by me. I can't remember the name of my client, but it's her name on my work. We collaborated for months. As with so many other topics I tackle, the connection between unethical business practices and trade liberalization became a subtext to my everyday life. So, of course, you can imagine my excitement when I received the good news: "thanx so much for uhelp ican going to graduate to now".
The author claims that his three primary customer demographics are "English-as-second-language student; the hopelessly deficient student; and the lazy rich kid." In the above case it looks like the first category. But what are the proportions? I assume that the lazy rich kids are mostly undergraduates or MBA students.