When you look at opinions on a free forum, where the get into teaching adverts usually are, people are more likely to submit a post containing their personal view if they feel more strongly about the subject. People who feel more strongly, therefore make more posts and this then appears to the reader that the majority of people posses those views. I am not saying every teacher enjoys their job, however, would you be able to say that about any profession?
I enjoy it very much. It really is down to the person you are. If you are thinking about it then I advise that you get some experience in a school to see what goes on behind 9-3. Teaching is an amazing job. You do much more than teach, you nurture, counsel, parent and care amongst many other things. If you decide to go for it, good luck and enjoy it.