With the caveat that you should never say never, but:
1. Boat shoes, pleated khakis, essentially anything obviously "preppy". I overdosed on that between grade 6 and 8, and have not touched it since.
2. Anything that has touched Ghulkan's body. I mean, maybe he is a cool dude, but really.
3. Cowboy boots. Cowboy hat. I just can't pull it off.
4. Jorts (Full disclosure: I had a pair in grade 7. They seemed stylish and practical at the time.)
5. Teva style sandals - they are useless, ugly, and stink like death. (Full disclosure: I had a pair, and wore them with my Jorts).
6. Vest worn casually - about 1/1000 people can pull it off and look good. It's not me, and chances are, it's not you.
7. Sheer anything - it's a no win situation. If you are not in perfect shape, you just look stupid. If you are, you're just a douche
8. Wifebeaters - see 7.
9. A Patek Phillipe (obviously, I would totally. But I just want someone to take this as a challenge and send me one.)
10. A beard - Again, I've tried. But instead of looking like a cool Chinese warrior, I looked sorta like the rat faced foil in Kung Fu movies who spends the entire time getting his ass kicked. Not a good look.
For anyone who put down "bootcuts", I call bullshit unless you are over 40, 35 if you are a young fogey.