@sidereal Once Upon A Time a company interviewed me (for a contract job), but it became clear that they didn't actually have a job, they were just after some free consultancy from the interview.
So when I got contacted by an agency a few years later saying that the same company wanted to interview me again I said:
"Fine, no problem. That'll be £500 up front for the interview, deductible from my first invoice."
That was, of course, the last I ever heard of them.