I've dealt with a lot of head hunters and contracting agencies over the years. After being sent on a couple of bad interviews early in my career I learned to take control of the process. Here are a couple of suggestions.

1. During your initial communication with the recruiter you should ask them not to submit you to any job without your approval. Some of them feel that once they've spoken to you for 5 minutes they have permission to send your resume to whomever they feel like it.

2. Get as much information as you need to know to decide whether you want to be submitted for a position. First of all, find out the name of the company they are submitting you to. It seems obvious but many recruiters are hesitent to give out this information because they are worried you will circumvent them. Assure them you won't do this and insist on knowing where you will be submitted. If the recruiter doesn't know much about the job then ask them to get more information. You should know enough about the job and company to at least know whether it's a possible match.

3. Keep notes on your conversations with recruiters and the jobs they submit you for. You do not want two recruiters to submit you for the same job. This can create a messy situation for the potential employer that would make it less attractive to hire you.

4. Ask for a brief phone screening before you go on an interview. This only needs to be a 10 minute phone conversation with the employer that will allow both of you to discover whether it's worth spending several hours doing an in-person interview. This step, in particular, will save you from wasting your time on interviews that aren't a good match for your skills/experience.

5. A lot of recruiters will reformat or even reword your resume before they send it. Most of them do this just to remove your personal information and to give it the common formatting style that their agency uses. Some will change it in an attempt to make it more effective. If the recruiter is good at their job, then this can be a valuable service. But I've also had recruiters change my resume so that content and meaning were altered. I now tell them that I want to approve the resume if they are going to change it in a non-trivial way.

All this being said, recruiters can be a very valuable resource. There are a lot of jobs that never make newspaper or online listings. This is particularly true with small companies that often farm out their HR. Recruiters and personal contacts are the only way to know of many opportunities.

My personal job hunting strategy is to send my resume out to as many recruiters as possible. The only cost to me is that I have to field a lot of phone calls for a few days. But since I learned to take the steps above I rarely get submitted for inappropriate jobs and I haven't been on a pointless interview in many years.

Good luck. And, as others have said, there is no harm in fishing as long as you can do it discretely.

-Dylan