I know what you mean. When I try to be careful about what I say in respect to the person I'm talking to I tend to slow down and be very deliberate. But I think people misread that as you thinking their stupid, that they couldn't understand that you think you're right until you slowed down your speech/made it more easy to understand. And also I think it has to do with communication now adays. So many people now think they're right about everything and everyone else is stupid or wrong, that others immediately respond to that.