CS:GO developers regularly determine which workshop skins will eventually make their way into the game. Selecting the creations of skinmakers for the next case, they determine their rarity – that is, the probability with which this or that item will fall out. Interestingly, this characteristic is not set arbitrarily – it depends on the appearance of the skin and its design features. 
For example – distribution of skin rarity in the case «Dreams and nightmares» .
As for the principles of selecting skins for CS:GO from the workshop, Valve determines in advance what types of weapons will be included in a particular case, so community members can create their work with this in mind. Also, multiple skins made in the same style usually don't take to the game at once. For example, four skins from the Neo-Noir series ended up in the game between 2017 and 2020, and the design for the UMP-45 from the same author is still waiting to be released.
Army quality
Army-quality skins can be similar to each other. They often use shades of the same color without contrasting combinations. In this category fall coloring books that are difficult to distinguish from each other at a great distance, and all the details are visible only to the player. Often for such skins is used texture, evenly covering the entire surface of the weapon, without emphasizing individual details.
Forbidden
Skins with a more contrasting pattern fall into this category. They use bright color combinations so that the pattern can be distinguished not only by the player himself, but also by those around him. Sometimes in the design of such skins appear optical illusions, for example, to create a three-dimensional effect on individual parts of the body.
Classified
Skins from this category are recognizable even from afar due to the contrasting coloring and expressive color combinations. Examining the skin that holds in his hands, the player can discern interesting details of the pattern, which is not just superimposed on a three-dimensional object, but fitted to the shape of the weapon. Those watching the player from the sidelines have no problem recognizing that he has a true rarity in his hands.
Secret
Skins with this characteristic – are the most recognizable. They are truly unique, so not only can they be recognized by teammates who are nearby, but also by opponents. In addition, the skins from this group are most notable for being designed for a specific gun. If for the army quality it can be enough just a memorable pattern, for the covert one you need a careful elaboration that takes into account all the details. For example, the characteristic feature of the Neo-Noir series is the image of a girl, but her outline changes depending on the shape of a particular weapon.
Interestingly, these criteria do not apply to skins developed by Valve itself. Unlike coloring books selected from a workshop, they may look too plain for their rarity or, conversely, appear too bright. But in any case, getting classified or secret skins by opening cases – is not easy. If you do not want to rely on randomness, use the store Lis-Skins.ru to buy any skins for CS:GO at affordable prices.