"ויבא יוסף את דבתם רעה אל אביהם" In 37:2 we start reading about the growing rift between Yosef and his brothers. Yosef woul dtell his father all the "bad" things they were involved in.
Why is this such a problem? As a parent, when one of my kids does something bad, I would like to be told so I could take corrective action. If my kid runs in the street or is seen doing something to hurt another child, etc. I would like to be told. So what was wrong with Yosef telling his father what they were doing? He wanted his father to be aware and take corrective action!
The reason it was considered bad of Yosef was because of his intentions. There is a way to tell over information for beneficial purposes in order to improve a situation and there is a way to tell over information when you are gloating or trying to undermine somebody.
Sometimes a parent will call up and say I saw your kid do this or that. If they have the intention of trying to help then their comments are appreciated and accepted. When their comments are in that gloating tone, so as to say your kid is wild or nasty or hurtful or you don't know how to raise your kids (and you can usually tell by the tone), etc, then the informations is resented.
That is what happened with Yosef. Yes the information was important and beneficial so yaakov could attempt to correct things. However his tone was one that indicated he was not doing it 100% with good intentions.