People should not be judged on appearance, but in reality they are.

Someone going for a interview gets dressed up, because they know they will be judged, evaluated. Go scruffy & dirty you ain't gonna get that job.

A friend of mind went to a doctor because she possibly has IBS, and is underweight. She wore black leggings with a black top & black coat. She smokes occasionally.
The doctors report (after a short consultation) remarked on her appearance and made much of the fact that she was dressed 'In black' and that he 'could smell smoke', and that she was 'underweight'.
His conclusion was that she was anorexic, and deliberately not eating.
My friend was fuming after reading his report. She is so not anorexic! She wants to put on weight, she does not see herself as fat. He came to this diagnoses because of her appearance, because she wore black! She just happened to wear a black top & leggings that day, it was no big deal.
She swore from that time forward she would only wear bright jolly colours to see her doctor.

Doctors can assume (wrongly) that if you look smart, clean and stylish with nicely applied make-up that you must feel OK.
They believe (wrongly) that if you felt real bad you would be too disorganised, too exhausted to care about your appearance, they expect you to look untidy, greasy hair, dirty, with no make-up.
It would then be noted that 'This person is not coping with life and needs help'
This is good advice.