I don't think that I've ever had an actual negative initial reaction (ignoring them thinking I'm wrong -- I don't think that's negative, that's an opportunity for growth and learning, maybe by me). I am, however, careful in how I say things. Specifically, I'm careful to avoid any criticism of other people's judgement. I talk about the project and the project only, never the people working on it. Handling people is the job of a manager, and I'm not a manager.