Fighters who wear their trunks up too high.

[Master]

You do sometimes see a referee point out what he considers belt line when giving instructions in the ring, the problem is the judges don't always comply with it.

Sometimes the same referee also penalises the fighter when they clearly hit the belt line. Also some fighters like Ruiz fake getting hit in the balls like he did with Holyfield, plainly cheating.

[shooter]

Check out McCrory's trunks against Donald Curry.
It may hve been a Steward/Kronk thing as the legendary Tommy Hearns wasn't averse to the high beltline.

Michael Grand it the Lewis fight looked like he was wearing a strapless dress.

[Jimanuel Boogustus]

DeMarcus Corley got hit square on the belly button against Cotto and insisted it was below the belt