Upvoted for this remark.

If I'm interviewing you, it means that we already think you are worth talking to. I don't want to waste either my time or yours. If what I'm asking you to do makes you uncomfortable, TELL ME! I can think of the last two people I interviewed who gave me a series of immediate "I don't know..." answers to a bunch of questions. They're happily (I hope!) working here now because we changed the interviews to go down productive paths to find out what they do know instead of beating our heads against a wall!

So true! Employers are investing so much time in the preliminary recruiting, filtering, and scheduling- by the time a face-to-face interview comes around you can guarantee they are interested in you. Candidates can make their job much easier (and perhaps land the gig) simply by anticipating their questions and concerns. Come prepared, ready to prove your qualifications and all their questions just might go out the window anyway.

Also in most cases the person interviewing you wants to be able to say yes. They need someone for their team and probably have other things they'd rather be doing than recruitment.