How to identify Bad friends?

It is very easy to identify good or bad friends, the friend who does evil about another friend in front of you, by taking some or the other thing, it shows that that friend did not tell your evil to any other friend. Must have done it, it is evident from the fact that what a bad friend he is.

Bad friends are those who taunt you about something or try to humiliate you.The hallmark of a bad friend is that they are jealous of your success, and will be with you in your good times but will leave you in bad times.