Vanessa Friedmanis Fashion Director and Chief Fashion Critic at The New York Times... (wikipedia)
Similar things apply when you are going to warm climates. In Los Angeles, where the sun is bright, some suit fabrics which look gray in London take on a strange greenish tint (in Los Angeles).
For women you would not want to leave your shirt undone, so that if you lean over you reveal something you did not want to reveal,
You do not want to do what one female banker did. She went to Finland with three-inch heels, but they did not work in the snow,
So you do not want scraggly beards, weird hair or anything else that people would be looking at instead of listening.
If you have got a jacket with a belt, you do not want to leave the belt undone, because it flops around and is distracting.
This is the potential start of something...awareness
If you treat your subject with seriousness and respect, other people tend to treat it the same way.
The important thing when it comes to grooming, as when it comes to clothes, is you do not want anything to distract from the strength and power of your ideas,.