The issue is more one of the prospect's obligations than yours -- as\r\nseveral people have intimated, the source of a candidate is indicated\r\nand retained. If the employer bypasses the HH, they're liable for at\r\nbest a very cool relationship, and possibly a "finders fee", which\r\nusually works out to a significant chunk of first-year salary (10% - 40%\r\nis a typical range, 1/3 wouldn't be out of hand).

Most companies retain resumes for a number of years, I think two is\r\ntypical. Some of this is legally mandated, and it's likely you can surf\r\nyour local bookstore's Nolo Press selection on employment law to find\r\nout what this is (the HR department is likely reading the same or\r\nsimilar sources). This means that you likely can't approach an\r\nemployer independently for a number of years after going to them through\r\na headhunter. This is among the reasons I consider my HH placements\r\ncarefully. If you submit through a flake, you're possibly closing off a\r\npotential avenue for you, for a number of years.

Note that even within the HH field, the contact accounting can be\r\nsignificant. I used to work through an account manager at Firm A who's\r\nnow working through Firm B, though I had communicated (four years ago)\r\nwith another person at Firm B. This came up in conversations with my\r\nprior manager when I was talking with him in my recent job search.

Your best employment bet is still personal references. I've\r\nlanded about half my own jobs via same. Random headhunter placements\r\nhave been among my worst experiences, HH placements with whom I've had\r\nan existing relationship (e.g.: body shop) tend to be better. There\r\nare a number of firms whose past practices have insured I'll never work\r\nthrough them (That "you'll never work in this town" speech is a real\r\nreputation killer, Hall Kinion -- even if you tell it to my hires, not\r\nme. Especially if it comes from both the recruiter and the\r\nrecruiter's manager.).

What can you do? Ask both the HH and the hiring\r\nmanager if they could give you an indication why the position wasn't\r\nfilled in the first round. They don't have to tell you, but they might.\r\nAnd you come across as someone who's seriously interested in\r\nthe position and on following up. The key is to phrase the question\r\nneutrally: "Any idea why the position wasn't filled / is still open?"\r\nrather than "Why didn't you hire me? / How did I fail?".