I ony bite my nails when there's a tear to remove the overhanging nail to avoid getting stuck in textiles or something.
Quote from Lan;1249477:
Dip them in water with hot peppers. Just avoid rubbing your eyes and you'll quickly learn not to bite them.
That would be a reason to start the habit for me. Nailbiting good! Though would you even notice the hotness if it's diluted in that much water? Just cut a habanero and stick your fingers in their juice.