3. Nail Biting
One of the most disgusting habits ever! Not only does nail biting affect your looks, it is also very unhealthy. You touch a great number of various things throughout the day and bacteria that stays on your hands and under your nails later on gets into your mouth. As for the beauty – well, who wants their nails chewed and ragged? Chew gum instead. Ask for professional help, do yoga or coat your nails with a nasty-tasting polish.