I once had a conversation with a recruiter that went like this:
"I see you're very qualified for this senior back-end position I have. Do you know HTML, CSS, and JavaScript?"
"I do, but those are front-end technologies, and I'm not interested in a front-end job at this time. Thanks, anyway."
"No, this is a back-end job."
"I think you have the definition of front-end and back-end switched around."
"You know, I'm looking at your résumé again and I think maybe you're under qualified for this role. I have a junior position..."
"Goodbye." (click)
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It's not just the emails. It's the constant phone calls, too. Software developers get tired of talking to "air-quote recruiters", e.g., "Are you familiar with... 'Hadoop'?"
I understand these guys aren't going to be experts, but given that most positions are found through referrals, some tech people just feel like it's not worth the hassle.