I am honest. If a college coach, or scout ask me for my opinion they are going to get my honest opinion. Building relationships on trust get's guys way more opportunities than it causes guys to lose opportunities. I wont be saying anything I haven't already said to the player and the parents I can guarantee you that.
Now having said that I have serious issues with any college coach who bases his decision solely on the opinion of one person. Unless he has a long time relationship with that coach and he has proven to be trustworthy over a long period of time. So if a college coach simply took the word of a HS coach to base his decision on then in my opinion that's a poor reflection on the coach not the player.
If a college coach got a negative report like this on a player from his HS coach it should only be one piece of the puzzle. What do his summer coaches say? What do his former team mates say? What do the players say who have competed with him and against him? What have your eyes told you when you observed him during games interacting with his team mates? What have other coaches heard and who did they hear it from? What have your interactions with the player told you? And what do the assistant coaches of his HS program say?
If this HS coach told you he said these things to the college coach and: He has never brought this to the players attention and assisted him with changing the behavior. If he has never brought it to the parents attention and asked for assistance in changing this behavior. Then the HS coach is a total clown and has failed miserably and doesn't need to be coaching.
I have heard of HS coaches trashing players before. I personally know of a couple of instances where a HS coach trashed a player because he simply didn't like the player. In both instances the information from other sources proved to be in such direct variance from the HS coaches comments it was discounted. I can tell you it's not an easy thing to tell a college coach the truth sometimes. But it is imperative if you want to be trusted to provide the truth on a player that is deserving of an opportunity.
If what your saying is indeed true that is very sad and a total failure from the HS coach AND the college coach as well.