I am constantly hounded by these people. They are no better than double glazing salesmen. If you're in an industry / professtion thats in demand they chase you. If you're not they are not interested in doing hard work to find you a job. They will (badly) look up a list of their available jobs (that have been placed with their agency) and see if you might fit. If you have engineer in your job title that means you will get calls for any type of engineering job, be that civil, drilling, pipeline, mechanical, analsysis.... I can't imagine they are any better with other areas of work.
They make commission of every scalp they get so they're not interested in what you want / need except to tell you enough to get you interested in moving so they make money.
If you're in demand its easy enough to find your own job. If you're not these guys won't go out of their way to help you as there is nothing in it for them.