Personally, I still shocked - and am mindful of the red flag - when they don't realize I'm interviewing them as much as they are interviewing me.
When we make a bad hire we do a post-mortem just like we would for a critical production bug. We adjust the interview process or evaluation criteria every time a bad hire is made.
We also give the same interview for every role. We spend 80% of the time asking the same questions, and leave 20% of the time for the free flow conversation and interviewee questions.
You cannot do a postmortem for failing to hire top talent, because you will never know.
What I want to say is that a bad hire is probably less important than missing out on a top candidate. Because you can always fire as soon as you find out. The other error cannot be corrected.
How would I know that during a round of interviews I failed to give an offer to Top Talent? What can I do if someone I think is Top Talent gets another offer we cannot match?
Sure, I can try my best to work against those very costly situations, but I never know how good someone is going to be until they are hired, so I don't have enough data to determine if I'm failing to hire the best.
I can, and we do, determine which candidates we hired that we really like and talk to them about why they choose the company and try to appeal to and find more candidates like them.