I have a colleage (female) she says "good morning sir" in the morning. My experience is that she has decided to say bad words later or straitly fight with me or want to do some damage.
Then i just ignore her as far as possible. But she get a little chance upto the evenig she invariably fights. Why this ? This is just to gain sympathy & with each person you can not be nice. You have to throw your animals insticts and negativity to a chosen scape goat.
This is the method, observe the person very close. Then greet them, show respect and then fight mecylessly. But one fine day this warrior will be known.