Is this bad??????? READ INTRO!!!!!!!!!!!!

so, when i meet someone face-to-face for the first time, i know within like 5 minutes whether i like them or not. and most of the time im right. and then in school they keep saying, get to know a person before you judge them, but its not like i do it on purpose, i just get a wierd feeling in my gut about certain people. i talked to my mom about it, and she does the same thing, and she says i should go with my gut. and i dont know if i should listen to what they say in school or to my mom. HELP!!