Being nice to someone you don't like isn't considered being fake - it's called being an adult.
Some people seem to forget that as working adults, we are not expected to LOVE everyone we come in contact with, but we are expected to be respectful and civil. I try to practice this every day when I deal with people that I don't necessarily like and often wonder how many other people practice the same thing. Also, there is a big difference between being nice and sucking up. I am nice to everyone I come in contact with and I don't give compliments unless they are deserved.
Do any of y'all run into this problem in your daily life?