I was listening to a podcast with Jim Rutt and he said that he encouraged people to give "bad news" and to not shoot the messenger. He was also against office politics and fired people for it. I wish more companies had this culture.
I've never gained the impression that that was anything more than lip-service. The two people I know of who dared to say something were shown the door. Quietly, discreetly, done in a way so they wouldn't dare to sue.
Therefore, imho, if you do report anything, make sure it cannot be traced back to you. Or just don't, it usually isn't worth it.