Exactly 10 years ago, my first job interview for a position as java developer:
Tech guy, asking me lot of deep questions about last java improvements, upgrades of newest web frameworks etc.
I answer very well.
He seems satisfied. He is about to leave, and just on the door, he turns and he asks this "just-one-more-question" in Lieutenant Columbo style:
"ehy do you know something about COBOL"?
Me: "well, ....yeees" (thinking: it's a programming language, only thing I know, plus I want the job)
He: "...and would you mind...." (some vague gestures)
Me: "...hmm...not at all..."

I got the job. All the project was about a huge legacy COBOL program. Almost no java.

I soon discovered that nobody inside the company wanted actually to deal with that project either....

Sometimes during interview you try to sell yourself, but it's actually the other way around, they are trying to sell something to you...