...to find if you hate someone's guts or not.
The next time that person tells you he/she has gotten something better out of their daily existence, maybe out of good luck, or maybe because of hard work, just detach yourself from your body, and watch what remark you give to that person. If it's a nice impressed smile, and words of congratulations that you really mean, chances are you're putting yourself in his/her position, and feeling happy for the person.
However, if it's just a nod, or a smile (forced, maybe), and "congratulations!!!", well, there you have it. You hate that person, or are in the process of hating him/her.