A friend is someone who knows you and loves you just the same

     I agree that in general you should accept people as they are-I mean with their positive and negative qualities-but in the case of friendship I think it depends on the type and depth of friendship.
     In superficial friendship maybe you only want to fill your free time with somebody, so you don't get very fussy about your friend's behavior; you mainly try to enjoy the time that you spend together, but things can be very different in deep friendships.
     In my opinion, real friends must somehow influence each other. They should help each other to develop spiritually. What's the use of friendship if you don't show any reaction to your friend's wrong behaviors and big mistakes. What's a friend for then?
     Therefore, in my opinion, if you realize that a friend of yours has a bad quality which is harming your friendship, you should tactfully deal with it. I believe the best thing to do would be to show each other the right attitude or behavior by your actions and not by giving direct advice. I strongly believe that in most cases advice is counter-productive.