Never trust people that when you see them at the first you go "He/She doesn't seam to be nice", because at the end unfortunately most of the times you are right. When someone, seams like that the first impression always matter the most. Even though many times people do act differently in some situations, but after those moments they are always evil, they are always their selves. So the outcome is that never trust and be open to someone like that. Always keep in mind that they are laughing at you, and they are what you thought they were.
Do not trust someone that looks bad, because he/she most probably is.