A long time ago I was playing in an orchestra used for a conducting master class given by Edo de Waart
who at the time was conductor of the SF Symphony. The participants were all young graduate level conductors. The piece was the first movement to Dvorak's New World Symphony.
A woman came out and started conducting. Her technique was stiff and she was unprepared. That much was obvious to everyone in the room but her. As she led the orchestra, 'Maestro' de Waart walked up to the podium and with a slight wave of his hand stopped the orchestra. "You are wasting everyone's time. You will never make it as a conductor. Who is next?" The woman stepped down and left the hall in tears.
It was the cruelest thing I had ever seen. Much more so than any "flame" I've read online. Her big moment in front of the master and he crushes her like a used tin can. Was he right to have done that? I have yet to decide.
The one thing that everyone there that I talked to agreed on was that it would either ruin her or turn her into a much better conductor.
Whenever one comes before a master and asks his/her advice, there is always the risk that he will give it to you. When he does, no matter how harsh or cruel or discouraging be grateful that he has. One comes to learn the way, not to feel good. If one cares about the toll it takes on one's pride, better to travel down another path.