It seems that every time I have a conversation with a coach who complains that some of his players have bad attitudes, I quickly start getting a sense that the coach not only isn't doing anything to make things better, but may be contributing to the problem in the first place. It is often easy for an outsider to spot the bad body language that infects so many player/coach relationships, but goes unchallenged and unaddressed because of the power that a coach has over playing time. If this doesn't make sense to you, start watching the coaches at games, and pay close attention to their body language and interaction with their players. See which team ends up winning. The coach who interacted with their athletes least, and displayed the better body language, probably came out on top.
One way to correct bad attitudes on a team is to give athletes and their parents a chance to express their concerns or air grievances anonymously during the season through a mid-season evaluation form.