The grill -- a symbol of wealth for hip hop artists ... and a fashion faux pas for much of the rest of Hollywood.

Check out 13 stars who learned the hard way that not all that glitters is gold ... or good.

13. Hulk Hogan

12. Khloe Kardashian

11.Rihanna

10. Kelis

9. Katy Perry

8. Harry Styles

7. Rita Ora

6. Brooke Hogan

5. Cara Delevinge

4. Lady Gaga

3. Madonna

2. Kylie Jenner

1. Ryan Lochte