A common HR thing that drives me nuts when I'm job hunting: the implicit assumption that all coding skills are language-specific, that there is no software engineering expertise that transcends command sets. That ten years experience in Java and another five in Perl mean you'd be completely useless on a project that uses, say, C#.

"Yes, there's a learning curve. But I've made harder transitions than this. I'll make you a deal, pay me 80% for the first month and at the end of that time if I'm not ... oh, wait, we're not actually having this conversation, because your HR monkey simply deleted my application."