Yes, even from relative strangers at the very first meeting seconds after that introductory handshake. Since general medicine basically governs everything that happens to your physical body, it's a subject that's reasonably close to everyone's heart.
And everyone's all too willing to share confidential information. Reasonably circumspect fellows would suddenly have zero qualms about baring their innermost secrets, not only about that dark secret ( possibly venereal ) wart they have hidden up in their inner thigh, but also about every other medical professional they have ever met in their lives.
Patient : I don't know if you know him but...
Paul : Not really, I mean we don't have a secret clubhouse, but why? Do you have a complaint about that doctor?
Patient : Yeah, there are rumours that he usually comes up with the wrong diagnosis.
Paul : Well that actually does happen.
Patient : How can la liddat!
Paul : Hmm... how do I explain? It's almost like throwing a dart at a board. Blindfolded.
Patient : Aiyoh!
Actually I've got a simpler answer.
Doctors are not God.
Hmm.. what in the world does this patient have?
No matter how much some of us ( looking at ya, cardiac surgeons ) wish we are. Although we might be pretty sure about our provisional diagnosis, that doesn't mean it's a 100% absolute. There's always some margin of error. Even more so when the signs and symptoms are oddly non-specific.
Yes, mistakes can and will be made.
But look, even the renowned physician Gregory House gets it wrong. Even with an entire highly specialized team of medical experts, a plethora of diagnostic scan machines and a reasonably intelligent patient with surprisingly specific symptoms. And obviously it doesn't actually take only half an hour to come to the correct conclusion.
Even then, they usually get it all wrong. Test the wrong drugs, try the wrong treatments, experiment with the wrong trials - usually ending with the terribly unfortunate patient almost at the brink of certain extinction.
So yes, doctors do make the wrong provisional diagnosis. Fortunately most of us also have an exhaustive list of differential diagnosis to follow.