That doesn’t sound pleasant. I never got the accusation vibe during diagnosis, but I got it a bit from my parents because to the uninformed, ADHD looks an awful lot like character flaws/moral failing/plain old laziness, and seeking a diagnosis then looks like finding a cop-out excuse for sucking at everything and not just trying harder.
Anyhow, as for how diagnosis works, it seems to vary a lot. In my case, I went straight to the psychiatrist with my concerns, and during the first appointment, I shared past medical records/evaluations that had noted behavior/socialization issues as a kid and teenager, and discussed my turbulent academic career and past and current symptoms. He diagnosed me in half an hour, saying I was a poster case for a girl with inattentive ADHD, and it was appalling it hadn’t been identified earlier. I would think that without the old records to back me up, it would have involved more questioning and symptom discussion. I was then sent to my GP to be examined for fitness for taking stimulant meds, and after the all clear, returned to the psychiatrist and got the prescription.
From what I’ve heard, that seems be kind of middle of the road for diagnostic process. Some folks have had it as easy as going to the doc and whining about not being able to concentrate and walking out with a stimulant prescription (this is how lots of students who may or may not actually have ADHD get their study drugs, and make actual ADHD sufferers look like frauds to the deniers). On the other end of the spectrum, you could be subjected to an involved (and expensive) evaluation process that includes stuff like a long multiple choice test about all your symptoms and then interviews with/questionnaires filled out by family members and current or former teachers. Sometimes you might get diagnosed in an indirect way. For example, my MIL was diagnosed by a neurologist – she had hit a stressful point in her career and had become extremely forgetful and unfocused, so we feared the worst and she got an evaluation for early-onset Alzheimer’s, which identified the long-undiagnosed ADHD that had finally overpowered her coping mechanisms, and found no sign of Alzheimer’s.