One way to judge a person is to observe.
If you have helped him or her a lot in the past, even to the extent of bothering others, such as your boss, you probably have done enough to earn respect from everyone.
At the point of time you witness him do something wrong and you start questioning him, watch out for his attitude. If he turns nasty even though you have the authority to report on him, you can easily judge his character – ungrateful, disrespectful and rebellious.
Through simple incidents in life, we can easily observe and judge people.
Befriend only with people who really worth it; but still, it will be good to give blessing to others.