Gray walls, heavy vaults, a minimum of furnishings and amenities - even the royal residences on the screen look more like caves than the dwellings of the richest and most powerful people of that time. But in fact, real fortresses look gloomy and abandoned, because no one has been in them for a long time lives.
When the castles were inhabited, the feudal lords who lived there sought to decorate their homes. The walls were plastered, painted, sometimes in rather bright colors, or whitewashed. The rooms were decorated with tapestries and paintings, and sometimes with fabric wallpaper. And this is not to mention fashionable (for its time) and expensive furniture.
Naturally, if you go on an excursion in an unrestored fortress, you will see it unsuitable for habitation. Over the centuries, the plaster has crumbled, the tapestries and wallpaper have decayed, and the paintings have faded. But this does not mean that castles have always looked like this.