There was a lady that worked in the ticket office at Hatfield (has been gone for some considerable time now, I might add) who must have seemed very nice to most people. She would smile, give information and she even did platform announcements - such as telling people that off-peak tickets weren't valid on the 0924 to King's Cross (they no longer announce this).
However, she had a darker side, which was discovered if you happened to be young, Chinese and perhaps wanting to buy a YPRC discounted ticket. Hatfield has a very large Chinese population, and many can't speak very good English.
She would speak to all of them in the most patronising way you could imagine, and even shout at them for not showing their railcard and pretty much anything else not done quickly enough. She clearly didn't like students, and especially Chinese students.
I know Hatfield did have a problem (maybe still does) with YPRCs being shared between friends, so she'd probably experienced many problem students, but you must still remember to treat the next person in a professional manner.
I bet most people would think she was sweet and lovely but it was like Jekyll & Hyde.