But a headhunter she’d been working with insisted that she was the top candidate and would be offered the job within a week, encouraging her to decline a competing opportunity. Then, he went silent, failing to return calls or emails. She never heard from him again.

“When recruiters think they can place you, you’ll get all their attention. If their client isn’t interested, you may get dropped like a hot potato without even being told why,” says Spiegel, founder of Rising Star Resumes in New York City.

This is just one of a number of recruiter horror stories. One executive was excited to receive a call from a headhunter and eagerly shared details about his background and experience, only to discover that the recruiter himself wanted to work for one of the executive’s prior employers and had only called to fish for information. In another incident, a headhunter told a job seeker’s current boss that she was looking for a new opportunity, recalls Avery Blank, a Philadelphia-based career coach.

However, the reality is that headhunters and search firms control access to some of the best paying and most interesting jobs. So rather than counting them out entirely, it helps to understand the different types of recruiters and their roles.

You should first know the different types of external recruiters that work with employers and job candidates. Retained search firms work with companies to find senior executives, typically directors, vice presidents, and above. They receive payment regardless of whether the job is filled, so they can take a longer-term view and they have the resources to actively seek out suitable candidates. Contingency firms receive approval to represent companies with job candidates, but only receive a fee if they place an individual in a job. Employment firms usually focus on lower level or specialist positions, sometimes on a contract or temporary basis.

Not all recruiters have your best interest in mind. Watch out for the following red flags:

They ask unnecessary questions

While recruiters may reasonably ask about other active job opportunities you are considering, if they start to probe about the interviewers and hiring process, they may be seeking to get contact names to insert their other candidates into the process. “This is an exceedingly common trick less scrupulous contingent recruiters use, usually followed with something like, ‘Oh, you must have met with Gene Krupa?’ which uses the natural human inclination to correct misinformation,” says Dan Ogden, who is a principal at New York City search firm Omnibus Consulting. “It is very, very common in contingent, high volume circles like information technology and accounting.”

They’re overly complimentary

If a recruiter seeks you out and besieges you with flattery, beware. They may “state that they have been ‘asked to call you specifically’ by an employer, but after speaking to the recruiter further, you get the sense the employer did not ask them to call you. This is a trick used by some recruiters to make you feel as if you have been selected out from the crowd when you haven’t. It’s disingenuous,” says Dan Binstock, a partner at Garrison & Sisson, a legal recruiting firm in Washington D.C.

You get the hard sell

Responsible headhunters want to meet the requirements of both the employer and the candidate so that it’s a successful, long-term match. If you feel pressured to consider an opportunity that you’ve dismissed, be skeptical. “This is a sign that the recruiter is only interested in making a quick placement. Contingency firms only get paid when a person starts, so they are interested in getting the position filled as quickly as possible,” says James Lord, managing director for Helbling & Associates Inc., a Pittsburgh-based retained executive search firm.

They insist on being an intermediary

“Any time a recruiter will not let a candidate communicate directly with the client, I think that is a red flag. We are catalysts in the process, but, ultimately, the candidate will be working for and with the client. Therefore, they need to establish rapport and a comfort level with each other during the process,” Lord says.

That said, you should never go behind a recruiter’s back and apply directly to a position that you heard about from a headhunter. This is not only unkind – it potentially cheats the search firm of a fee – it could get you blackballed by the employer and the recruiter.

They’re cagey about details

You can and should ask a recruiter how many other candidates he’s presenting to the employer, how you compare with them, and the timeline for a hiring decision. “If you don’t get a straight answer, you may be in the running just to make the others look more desirable,” Spiegel says. “Bow out if the headhunter obfuscates.”