Somewhere along the lines, many people developed the notion that if your child bites, the best solution is to bite back. Don't treat fire with fire! It's likely to make the situation worse.
One reason that biting your child back isn't good practice (besides the fact that it is considered child abuse) is that it is confusing to kids. Sending the message, "You can't bite but I can," just doesn't make sense.
Kids learn way more from what you do rather than what you say. So when you show them that you bite, it's teaching them that it's okay.
Also, if it works, it is because your child is choosing not to bite out of fear, not because he necessarily recognizes it is a bad choice. The best discipline practices teach kids new skills and show them what to do instead.
If you don't want your child to bite, he'll need to know how to use his words, resolve conflict, and manage his impulses. Teach him healthy ways to solve problems and how to successfully use his words.
I recently came across a good book, The Biting Solution, which offers many different strategies to help parents stop biting. It's a great book that suggests parents and caregivers work together to address the problem by teaching new skills.