I got an introductory e-mail from a recruiter through linkedin, and since the company has brand visibility, I thought why not. I was probably already setting myself up for a complete waste of time as I already worked at a premium engineering company in NYC and had no intention of moving to the west coast.
After responding, I got an e-mail from a second person sent to my personal account. After going back and forth and rescheduling (and canceling once), later I got a response saying that the position had been filled.
Then almost immediately a third person wrote to me offering me a chance to continue to interview for another position for which she thought my skills would be good. After a 20 minute phone call, the next day I received an e-mail that her hiring manager (and her team) had decided that I didn't have the right skills for any of their vast array of positions.
I let the entire thing go as 'instant karma in a plastic bowl'. Ultimately I was wasting more of my time than theirs. No regrets whatsoever.