I don't think in most cases you can. Even recruiters who are good people and technically savvy enough to help you find opportunities you want are at the whims of agencies, very large HR organizations, and the ups and downs of the market in the city they are focusing on.

As far as I can tell, recruiters work best when you want to work at a large non-tech company, because smaller companies can rarely afford the finders fee, and tech companies are starting to move toward having recruiting in-house. You might luck out and find a mid-size tech company that is using a recruiter because they haven't built up internal recruiting yet and are growing faster than they can hire current employee's friends, but that's probably a small slice of the overall market.

Recruiters also seem to work better for early to early-mid career folks (less than 5-7 years of experience). A lot of the work that they are doing is in the space of differentiating individual candidates, and using their personal relationships with hiring managers to get you an interview. If you're senior, with a decent github account and a reasonably impressive work history then there is honestly not much the recruiter is going to do to sell you, beyond maybe standardizing your resume into a familiar template or something- and you'd save a lot of money paying a fixed fee to a resume service if you need that.

The final bit about having luck with recruiters is that it depends a lot on the technology you're using. There are recruiters who specialize in hard-to-find skills, but the majority of recruiters are hiring for whatever 3 technologies have the most keywords in their database. This is where the adverse incentives come in. Recruiters are hiring out of a very large talent pool, because they are focusing on tech that has the most hiring volume (so usually something that was popular a few years ago, everyone knows it now, and it's being used in a lot of existing or legacy applications). They are going to have mostly undifferentiated early-to-mid career folks out of a very large pool of people who know a very common technology. In that case, they are incentivized to maximize their own revenue, which means if they are on a finders fee they want to get butts into seats as quickly as possible, and if they are contract-to-hire they want to bring people in with the largest gap between the candidate and employer rate (they want to pay you as little as possible and charge the client as much as possible). You're essentially seeing the same problem that you have in realty (http://economics.yale.edu/sites/default/files/barwick_confli...)

As for the firms that specialize in hard-to-find talent, there are a slightly different set of problems. The specialty recruiters I've worked with have often worked a much broader set of clients, and have much more shallow insight into the actual workings of the company. Since companies hiring people for harder-to-find tech stacks seem to be much more selective about candidates and hiring fewer candidates, the relationships the recruiters have helps you less. Because the recruiters are placing fewer people they want higher margins on you, so you have more to prove as a candidate to ensure the companies think you are worth the price. I've also found, anecdotally, that when I've worked with specialty firms, they have a lot less insight into things like company culture than run-of-the-mill recruiters. Again, if you have specific experience you can point to of success using the tech that companies are hiring for, and the ability to actually do the market research to find companies that are hiring for what you want, I think you're better off going directly- but recruiters can help if you are trying to pivot into a new specialty.