I find that calpol25's first point is what I tend to follow. When I write critique's, I'm honest. I don't honestly care about if the director/author of the work is gonna read it - I have the write to say what I think, as long as it's not abusive or hurtful.
Sometimes we have to agree to disagree with some people, which may happen on your own Hubs. Be sure to steer clear of what you're not interested in, and get involved in what you are ^^