It took 3 days of customer dev to realize my idea sucked

...but this idea is still an enormously entertaining excuse to turn the tables on recruiters, and subject them to a sales pitch right while they're in the middle of pitching to you.

In other words, some annoying recruiter delivers a cold call sales pitch to you. Then, when you realize the call is a solicitation, you get to interrupt them, while their in the middle of their sales pitch, and solicit your service to them, and reveal exactly how irritating they might've been, by irritating them in kind.

  > Hey, would you be interested in--

  Hey, you sound like a recruiter! I have just the kind
  of thing you might be interested in! It's a recruiter
  service for recruiters! Would you be interested in a free
  trial.

  > Erm, no thanks. But I do have a job open--

  Are you sure??? It'll only take less than a minute to 
  get set up, and in no time, you'll be recruiting with 
  recruiters just like you, all over the world.

  > Um, I'm not interested. 

  Okay, but could you take some time, and respond to my 
  brief survey? This is a questionnaire on why no recruiters
  seem to be interested in my service.

  > No. Thank you. Goodbye. *click!*

I think, when it comes down to it, you can't ask the recruiters directly.

They're the subordinates, and they don't make decisions about how their jobs are carried out. They perform the leg work, but probably at the behest of a manager.

It's just a day job to them. They'll find a way to say "no" anything they perceive as another layer of "extra work", and assuredly find some way to justify avoiding it. I know I do.

If you really want to make money, selling a thing no one wants, or needs, you have to ask their bosses, who will then saddle the bottom-rung recruiters with a service that they might not opt-in on themselves. Why should a boss care? They don't actually do the work themselves. They never get their hands dirty.

And, think of it this way, recruitment services are middle men to begin with. It's already an industry no one wants or needs. If you're selling an add-on (that, ostensibly, based on your ad-hoc 8-person survey, no one seems to want or need) to a business (annoying recruiters, that no one wants or needs), then you'll probably see some luck by targeting the leadership of the industry that no one wants or needs, because those are exactly the kinds of people that are probably most aligned toward a mindset of mutli-layered make-work inefficiency.