I wrote a fairly lengthy post on the fundamental flaws within the recruitment industry that perpetrate the shady, substandard behaviour that's so prevalent.
http://hackerjobs.co.uk/blog/2012/6/15/all-that-is-wrong-wit...
The best recruiters out there tend to share a handful of commonalities:
* Specialising in one or a small number of languages
* A decent comprehension of said languages
* Strong connections within the geographic tech scene they work in
* People who are more driven by helping people than by financial reward