Ask HN: How do you do customer validation for a "toy"?

In his essay "How to get start up ideas", PG wrote that one should build something small number of people want in large amount. He also writes in the same essay that building something that looks like "toys" often produces good ones. It's cool; users love it. But it doesn't need to be important. Can something be a toy and still some people want in large amount (without being important)? How do you do customer validation for such a product? Or, do they represent 2 different customer validation approaches for 2 different markets (such as enterprises, consumers)?