Vanilla Prison Guards have a uniform purple look, which I don't mind at all—I consider that part a sidegrade. However, these skins also include a direct improvement from current Prison Guards:
In 2010, Prison Guards were updated to have a Shotgun alt skin, like other Soldiers. This skin is strangely done - It replaced all Prison Guard textures with a uniform gray that is colored appropriately by the $selfillumtint variable. This makes their eyes awkwardly "off" from both their original appearence and how ordinary shotgunner eyes look, and messes with the other, already colored $selfillum elements on the models. Alongside the different arms, this skin fixes all of that by giving the two types of Guard their own texture sheets - one with the original, pre-2010 eyes, and one with the eyes from ordinary, post-2010 "clean" shotgunners. A comparison image is included.