I don't think good job interview is about answering right or wrong questions. It's more about talking with human you could work with and if that human is able to think his way out because it's engineering job after all.

I am contractor as well I only did job interviews as a side quest and I also frequently fail my job interviews, there is nothing bad there.

Personally I didn't like 90% of job interviews and there were plenty of them. Most of those people tried to convince me they are smarter and better then me and I am lucky I am speaking with them. But unfortunatelly that's how it looks like.

Most people that excpect right or wrong answers are just morons in my opinion because programming is about being wrong 90% of the time.

Good Luck