I echo what Alice Ann Meyer said in her article:
"If you are the parent whose child says another child looks funny or scary, don't simply say, "That isn't a nice thing to say." While you are right, it's not nice, simply saying that and walking away still isolates my child. The next time follow that statement up and tell your child, "I'm sure he's a very nice boy, let's go meet him." Please, come introduce yourself and ask my child's name. I assure you, we don't bite! My child is just like yours; he can be sweet, loving, throw temper tantrums, and be a handful. And I assure you, I am just like you; I am a parent learning my way through this.
If your child is curious and doesn't say anything mean but still notices he looks different, please, introduce yourself to us, ask us our names! Include my child in your world. I promise you, he's not scary, he's just a little boy."