If you make libelous statements about a person that causes damage to his or her reputation, business, income potential or brings pain and suffering to him or his family you can be sued.
The Internet is not exempted from the libel and slander laws of this country. I am speaking as an old reporter to had to remember the libel laws when writing my commentaries.
You might get away talking about a public official or a celebrity, but there is no absolute certainty.
Finally, Hub Pages could possibly be held liable for your comments.