Much like when i conducted interviews, if they got to my desk I knew they could do the job (track record) so my process was more about how they fit into the culture and how their people skills were (indirect questions and general conversation)
If you bring a Gruden, Jimbo, Peterson etc and interview they will be insulted. You already should know their coaching style/ability. If you bring as Asst in or someone with very little track record thats different.