Dear Sir,
If a headhunter who is good in his/her work can cook a story on the phone, then to make it more genuine can also send details in writing, which can be satisfying enough. That isn't a difficult work to do.
"It's because of such practices that the whole business of recruitment is in such a mess."
I have a little different opinion out here. According to me, it's not these practices that have made it a mess; rather, it's the demand vs. supply factor, quick delivery, and cost minimization factors that have made it a mess. Even though people realize that they have been used to extract information, the intrinsic desire, the need to have something better, makes them/will make them fall for it again by some other headhunter in the long run.
As you rightly said, I would appreciate if some other people in the headhunting business can share their thoughts/views on the same to educate us more.