I was wearing a red shirt once while helping another dog owner to socialize her rescued dog, when said dog bit me on the arm.
To the dog’s credit, he immediately realized he’d caused a problem, and calmed down. To my discredit, I was standing exactly where people tell you not to stand when socializing dogs (between two dogs is where you don’t stand.)
The upshot of which is that I didn’t have to throw the shirt away, even after a few hours of visiting the doctor’s office to get a few stitches in my arm. It was red already, and the blood, even when dried, didn’t make much difference.
But if I’d been painted all red, well, there’d have been an issue.