I have exactly one that I think is good in 21 years in the field. He actually understands his candidates at a moderately deep level and I can get on the phone with him, describe what I'm looking for, answer his questions, and a week later get a handful of resumes with his notes attached after speaking with the candidates.

His "secret" is that process, which also allows him higher than average access to passive job seekers. Let's face it, many (not all, but many) of the "best" candidates already have a sweet gig and aren't pounding the pavement looking and mindlessly applying to every job posting. This recruiter calls them and they take the call, because he's not just matching asses and seats like it was a musical chairs problem.

Candidates like him (he placed me once 17 years ago) because he's not perceived to be a time-waster, and hiring managers like him because I get better candidates through him (albeit at a lower volume and I "can't afford" him for every role).

That's responsive to your first sentence; to your second sentence, I generally agree. I have the luxury of having a strong in-house recruiting team, who are willing to selectively and smartly use outside agencies when it makes sense. As a result, I get to direct the flow of nonsense from outside agencies at my in-house team. ;)