There are some things we wish we'd never discovered about beauty — like the fact that aging starts at 25 and whale vomit comes in fragrances — and you can file every one of these nail facts in that category. Kelly Ornstein [1] at Valley Nails Salon [2] in NYC gave us a dose of gross anatomy. Warning: the things you read below might make you gag, but we feel you need to know for safety's sake. You could be committing a major cuticle crime . . .

1. Hangnails Could Cause an Infection: Those stiletto nails are cute on Instagram, but there could be all manner of germs lurking under your tips, including trace amounts of fecal matter and staph. "Having cuts and sores on your hand from hangnails makes you more prone to infection," said Ornstein. "A lot of bacteria will travel from your fingers to your mouth, your eyes, your nose."

2. You Have TONS of Nerves in Your Fingers: There are more nerve receptors per square millimeter in your fingers than on your arms and legs. So that is the reason a cut at the salon can hurt like a b*tch. You can avoid bleeding hangnails and cracked fingers by moisturizing your hands often. "Not tending to your nail care will cause all the chipping, the cracking, and ripping of skin," Ornstein said.

3. Assume Everyone Is HIV+: "There's the universal precaution in the nail industry that you assume everyone is HIV+," Ornstein said. "You are coming in contact with bacteria that can potentially have blood and infection, so we have to take measures the same way a tattoo industry would." As a customer, you should keep a close watch that instruments are not shared between clients and that they are disinfected between every use.

4. There's Skin Under Your Nails, Too: The hyponychium is the skin that you can see growing on the under side of your nail. "When you clean under your nail, sometimes there are little white frays, which might interfere with sealing the free edge," Ornstein explains. Use a small buffing block [3] ($6) to clear away the hyponychium debris or push it down in order to get a longer-lasting manicure.

5. Biting Your Nails Can Cause Scar Tissue: Nail biters, beware! If you continue to chew your nails, over time you could end up with fingernails that curve upward and numbed digits. "When you bite your nails, you're doing damage to your nerve endings, which draw sensitivity," Ornstein explained. "Some people bite it down so much that they build up scar tissue there that affects the nail bed, so it can grow upward or at an angle."

6. The Mechanical File Kills Keratin: Run if your nail tech pulls out the Dremel (the electric, rotating nail file that requires a face mask). Buffing, sanding, and filing too much can slowly chip away at the keratin in your nails, causing the "ring of fire." The ring of fire is a red semicircle that appears under the skin near the tip of the nail. "If you oversand or overfile, you'll start to see the blood cells underneath your nails," Ornstein explained. "You have to wait for that to grow out, and it's going to be paper thin and painful."

7. Microtears Are Why Your Nails Break: In addition to applying cuticle oil [4] ($20) and hand cream every day, you want to keep your eyes peeled for microtears. These are the little pieces of nail that snag on sweaters and eventually turn into cracks. Use a metal file [5] ($5) to pass over the edges every two days or so.

8. Soaking at the Salon Will Shorten the Life of Your Manicure: Say no thanks to the premanicure soak. "You shouldn't soak your hands, shower, or do the dishes, because your nails absorb water and the nail plates expand," Ornstein said. "Then the polish doesn't hold on, because the nail plates shrink back down [as they dry]."

9. It's ILLEGAL to Get Your Cuticles Cut in NYC: Depending your state regulations, it may be illegal to cut your cuticles [6]. The live tissue around the area should stay, while the white area that is lifting away from the nail can be trimmed. That's the dead skin. It's against the law because cutting cuticles makes you more prone to infection. As an alternative, use a cuticle remover [7] ($20) to soften the skin, and push back the area with a rounded cuticle pusher [8] ($5).