I feel that you don't have to beat someone over the head and break them down to get them to learn. Yes tell them if something isn't right or that it wont work the way they are doing it, but there is no need to belittle them. So some people may not get it though their head that what they are being told is for their own good, but those are the people that get left behind.
When Nick told me that the way I had designed that knife looked wrong, he did it in a clear way that wasn't demeaning and gave me the choice to take his advice or do my own thing. He didn't pussy foot around, he gave his views respectfully. Now if I had chose not to listen to him, I doubt that he would have ever given me advise again. With fast14riot's example he is being paid to teach these people, and I am sure that when he instructs someone a way to do something on the boat he does it in much the same way, its not till after they argue about not understanding that the gloves come off. I am sure that if he hadn't been paid though that he would walk away from the argumentative student. Mind you with what fast14riot is teaching there is no option to choose to listen for the student, its a case of listen or someone could die.
Lets say in your town there is a teenage kid that made the most unbelievable knife shaped object from a piece of wood he found in the park and some mild steel that was in the neighbors recycle bin and he did so using files and sand paper on his own, on the other side of town there was a kid that had good steel, and all the best tools available to him yet he made what looked like a prison shank. Who would you rather teach? How would you tell them what they did wrong? Now lets throw something else into the equation, the first kid is one of those people that are naturally good at everything they do, but they don't have the ambition to take it further, yet the second kid is an open book and wants to do better and will listen to anything you have to say and will go right home and try it. Ideally a mentor would get a combination of both kids, naturally talented and an open book willing to be filled with knowledge.
I am one of those people that believes in constant learning and that there will always be someone out there that knows more than I do and is better than I am, but I am also always challenging myself to be that top dog. I can also be pretty pig headed too, try to belittle me or smack some sense into me and you will run into a brick wall, or nothing at all because I would be gone. Yet treat me with respect and teach me as an intellectual equal I am as easy to get through as the air around you.