I think graphics cards and settings are a big part of it. I have my settings down pretty low because my laptop likes to get pretty hot after running sims for a while, and some sims and animals look very strange when I am not scrolled in all the way.
I'd double check your drivers are up to date, maybe adjust your graphics settings, it may fix it. Personally I can deal with the occasional weird looking animal vs having to turn off the game because the computers running too hot lol.