Originally Posted by Glitchy
As for models... it's a bit more stricter in policy than skins. Due to Blizzard's short sightedness on fence and gate collisions built into only the model itself and exploiters... model switching has caused modding to take a few steps back. Why? because exploiters switch the gate models to a box or some other small object.
Using model switches or skins to give yourself an edge or to exploit/bypass things is strictly prohibited! That means no skins that let you see your enemies from great distances, stealth, invisibility, etc (like having them all bright pink or something) herbs brightly colored for easy spotting, changing the size of nodes to be able to mine from greater distances, modifying walls or fence models to bypass them, etc. If it gives you an advantage in anyway it's against the ToS.
If it's just a visual change (just for looks), as much as it may irritate Blizzard they aren't gonna pay much attention to it Because it does not exploit the game or other players.