"When trying to set people straight - expect a battle. That's why I don't do it, I don't find pleasure in setting strangers straight."
Right.
Everyone, even us, have powerful belief systems. For most, regarding healing, their belief systems are so powerful it would literally take an act of congress for them to believe otherwise.
It is just best to remain silent unless they ask. Or, perhaps if one has enough respect and clout, it could be possible to short circuit through their limited belief systems.