This reminds me of an old trick from the Call of Duty 4: Modern Warfare days. You could edit the player model skins locally if you had the correct Photoshop plugins installed. Players would just spray over the character model skins with blaze orange so you could pick people out from across the map, even if they were hiding in deep vegetation. Eventually the 'pro-mod' developers caught on and implemented some client side hash checking but the public non 'pro-mod' servers were never protected against this afaik