You may be asking about things because you genuinely need to learn/understand something, in which case doctors are often eager to explain their stuff.
Or you may be asking questions trying to figure out if they know their craft, have run into difficult cases or complications to assess their level of expertise. That's a different story.
I once made a mistake of doing the latter, though I did it because I was facing an op and was quite disconcerted perhaps even frightened. At some moment the doctor looked at me with a special look and told me to go consider what I learned today and decide if I was ready for the whole thing. Then I knew I asked too much and all the wrong questions. Given that he was a very experienced specialist, was the chief doctor of that establishment and overall well recommended, the mistake was mine.
But in the end it all worked out rather nicely with no grudge-holding.
I think that is ridiculous. Last time I had a mild dental surgery I asked my dentist how many such operations she had performed and how many she had botched up. She not only very patiently and willingly answered by questions but also told me that she had a failure rate of 12% which was industry standard.
If dentists, car mechanics and your local gun dealer refuses to answer question there is the good chance they really dont know their own shit.
But yes, if I were considering dental surgery, I'd certainly want to know that number...
How do I know if the person I'm talking to is one of your "professionals," without asking these questions? I need to weed out the pretend professionals.
If you need a whiteboard or tests, to tell they are a professional then you may be doing something wrong. I can talk to a person and within 10 minutes tell you if they are a good developer or not. Perhaps it's a gift, but I suspect not, what I suspect is people focus on the wrong parts of what makes a developer a good developer.
People focus on the mechanics of development. Do they know syntax? Do they know the API?
In my time I have forgotten more syntax and API's than I know, I used to be a top notch Pascal developer and could be again in 2 weeks same with Delphi, but today I would be hard pressed to write a line of it. But people get hung up on this, they think a whiteboard, disconnected from information, somehow simulates reality; meanwhile we all use Google, before that it was the development library at your company, Barns and Noble and a host of other printed material. The reality is memorizing little used portions of a languages API is a waste of time (the platform is going to change). For 80% of applications built you are going to use the same simple patterns in whatever platform is being used.
The key is to focus on what you are realistically going to have them do. If you are hiring a CRUD developer they should have a good handle on Data access, Relational or NoSQL theory and web/mobile technologies. Don't ask them to write an algorithm that factors prime on the whiteboard when no one is ever going to write that and even if they are, they are certainly not going to do it in a disconnected environment.
I look for three things, intuition, an inquisitive nature and motivation. Those are the three things that cannot be taught. It has yet to fail me other than the above mentioned anomaly.
People can't talk the talk about specifics of industry experience if they haven't walked the walk, and that will become obvious in normal discourse around the matters of job role itself and their related experiences. You can be inquisitive, but starting off with CS101 quizzes is just condescending and wildly irrelevant to the actual position.
When I'm being interviewed, I respect the interviewer for demanding hard data, instead of just checking who talks the talk.
People have personal projects, accounts in social networks, personal blogs. Make a short list of candidates than go digging. You can soon get a good idea of their abilities and how far they are progressed on their professional evolution path.
That research will also quickly tell you if someone is a jerk. Read what they say and how they are saying it and you will learn all you need to know about their social skills. It's a more precise test than an artificial environment of a face-to-face interview when everyone tries to play an all-around nice person. But the thing is, you can't be a nice person 9-to-5 and a complete jerk in your off-hours. A jerk is always a jerk. Better observe them in the wild when they feel nobody's watching them and they can behave naturally.
It also works the other way. I sometimes encounter overall rude people online who share in passing what company they are employed at. I always try to remember the name to not mistakenly end up there.
It's entirely possible that the person who has gotten that far in the process literally cannot code Fizzbuzz. It's not an insult to be asked to do these things. It's a reality caused by the fact that some people can BS their way into anything, the hiring process at most companies is deeply flawed, and usually not the fault of the people you are talking to in the interview.
Obviously anyone who is that offended by this has never seen the other side of the equation where you've hired someone who turns out to be completely incompetent despite appearing to be very knowledgeable and smart in the interview, and now you've invested a whole lot of time and effort and money even if you are able to cut the person loose quickly. It happens. A lot. And it's often not because the hiring managers and other interviewers are idiots or otherwise failed to interview the candidate well.
Academic institutions generally don't teach people to code. It's always a personal quest. You can tell a lot about somebody who's graduated but never gone any extra mile. That should be the basic filtering criteria.
I too have seen people studying at CS departments who were useless at coding. I even helped some mates with their assignments so that they wouldn't get thrown out having invested several years already, though our field of study was not purely CS but more the hardware side of things so graduating as a bad programmer wouldn't be a terribly bad thing. Yet I know for certain none of them ever planned to be looking for a job as a programmer. And if you investigated their programming accomplishments you would quickly find out they should be passed on.
I also noticed that people who are smart and even brilliant do graduate with real programming skills but without personal projects of any sort. The thing is, they may join in as an ordinary programmer but do not plan to stay there long, meaning to quickly move into management or a business branch. You probably don't want them either.
Some preliminary research is always the right thing to do. You won't believe how many times I arrived at an interview and watched the HR turn over my resume to the interviewer for the first time ever, so he had to quickly scan it to get an idea what to discuss. With that approach not much can be accomplished on the hiring track.
When a professional comes in, he expects to be treated like one. Most people learned to solve basic coding problems when they were at the university like 15 or 20 years ago. Today, 20 years later you should be discussing other things. Otherwise, you're basically starting a dialogue implying the guy slacked off for 20 years inviting him to prove otherwise. It's just no way for two grown-up professionals to approach things.
On a side note, try this: make a appointment with a highly reputable dentist (like weeks or months in advance) then go and try asking him some basic questions implying he might not know his stuff. You'll be shown the door in about two minutes, and possibly you'll get a lifetime ban in that establishment.
Why should software developers accept to be treated differently? And yes, there are lots of incompetent dentists and doctors of all kinds. Why do they have more respect for themselves than software specialists?