Yes and no?
Orchid roots are different than other plant's roots, they have a covering called velamen which helps along with water and nutrient absorption. In many Orchids they are sort of grayish/whitish and turn green when thoroughly wet. When I water my Vandas, I keep watering until I see the velamen turning green. So If I might see a whole clear pot filled out with green roots, I might take a look if that plant truly needs watering. But to me it is not totally clear if white roots indicate the need for watering. I am not sure what medium is in that pot, are the roots facing totally away from from the medium and show me gray/ not green because of that? I don't know!
