I've voted down a hub but not an answer. The only reason I voted the hub down was not because it was purely commercial, but the content and pictures were big time OTT. I'm not a prude by any means, and generally believe in live and let live. But this particular hub was revolting.
Other than that if I don't like or agree with a hub or an answer I just leave it, and I feel that everyone is entitled to their opinion. The only time I might vote an answer down is if the response given is being deliberately vindictive/hurtful to the person asking the question.
The only time I was angry was with one of my own questions - I think it was a science kind of question. I got really good answers from quite a few hubbers. But there was one - there always is - who was obviously 'up himself' big time and his response was really in the mould of how stupid I was for asking such a question. If I had met him in publice I probably would have slapped him. He was so arrogant and offensive that it really got my back up. Anway I got it off my chest and responded to Mr ego-clown and told him what I thought of him. I didn't receive a reply back.
So I wouldn't worry about if some people vote you down - I think some do it for a power trip!