is horrible at their job. The smart, talented PhDs know that their work will speak for itself. The crappy ones try to rely on their "I have a PhD" status.
I've known hundreds of PhDs. There is a whole spectrum of intelligence and skill. The degree alone tells me nothing about how much a person is going to know or be able to do. BUT if I call a PhD by their first name and they correct me and say, "It's Doctor _____." I know they are insecure and not any good in their field. It's a big red flag.