Some apparel looks bad on any man. Some things look bad on some men, but not on others. What apparel, in your opinion, looks bad only on men over 50?
Ill fitting clothes look bad on anyone. As long as your being reasonably fashionable, or wearing something timelessly styled, and/or dressing up or down to the occasion, you might not be the best dressed, but you probably wont be the worst.
For the gent approaching or entering into his 50s
1) Tailored, not fitted - all your clothes should be adjusted to your mature frame. Both work and casual clothes should (at minimum) be correct in length; the legs on your trousers / jeans / khakis and the sleeves of you jackets / blazers
2) No "cargo" anything (this is really an "over 30" item)
3) The bill of your hat always faces forward
4) "Novelty" tee shirts of any kind are prohibited
5) If you are belting your trousers above your navel, you have gone straight into your 80s