I'll often get calls from recruiters telling me they've found a position for which I'm a perfect match. And then they explain it's a senior developer position requiring 5 years of experience, when it's very clearly stated on my resume that I'm a college student looking for an internship.
I've gotten similar e-mails and calls recently, based on a resume I posted to a job site 5 years ago, trying to match me to positions with requirements I don't remotely match. Further, I'm now a full time stay-at-home parent, which is my dream career. What's sad is, when I tell recruiters this, on occasion they'll still try to convince me of what a great fit their position would be.
Sort of. Remember they have two sides of the database: positions need filling and candidates available. If you reply to whatever they send you, they can drop you into the second bucket. So there's benefit to them (maybe even to you) even if the position isn't a fit.
They just keyword search resumes.