I agree that facial expressions would matter if you are doing a front-office job, such as that of a receptionist, ticket-booking staff and even a secretarial job as these are all roles of people who are the first seen & met. Basic good manners (saying things like 'May I help you', 'Please wait', 'Yes, madam, I will try to get this done as soon as possible', etc) and a soft-spoken voice with no rudeness are also definitely what defines a pleasing personality.
However, I completely disagree with what K Mohan implied in his statement "Normally those who are educated more won't abide by others." Care to explain that odd view and in what way it is relevant to have a pleasing personality?
When people come at you with their worst, you should come at them with your best (advice given to Selena Gomez by her mother, quoted in Time magazine.)