Really, people? You're going to discriminate against employees based upon this?
Part of running a professional workplace involves not letting your employees decorate it with f[inks]ing cartoon ponies. Problem is you couldn't set this rule without a wrongful termination lawsuit unless it applied to basically all custom desktops and cubicle decorations. I mean you can't say My Little Pony is not OK but Pokemon, Transformers, Hello Kitty, and all sorts of anime and video game stuff are OK. But our site outperforms other sites that do have such restrictions and tighter dress codes creating a bland work environment, and our division manager in a meeting once even told us that he partially attributes that to our site increasing morale and not pissing off employees with such rules.
Also you would seriously fire the girl who has a picture of her daughter playing with her MLP dolls as her background? I doubt even most Republicans would approve of that.