I don't think its a glitch, you actually have to click on the message and hit the agree or disagree button, for votes to be recorded. More likely to just be spiteful people, human nature is so wonderful sometimes;)
For me, I just igore them, I think that everyone has a valid point of view, even if a persons view differs from the others around them. As long as the TOS are followed, people should be able to post their opinions, without fear or favour.