Not "criminal mastermind", but do enough hiring and you will run into a lot of people who are convincing conversationalists but clearly haven't written much code in a very long time.
In a couple cases I gave these people benefit of the doubt and gave them a backup take-home problem (super trivial, 5 minutes for experienced engineers). They always came back with a solution, but when you asked them to walk you through it they couldn't really tell you what they wrote.
I understand that test anxiety is real, but having to discuss your code with others on the spot is also part of the job. If someone can't discuss even the most basic fundamentals of programming in a conversation, you can't dismiss it all as anxiety every time.