It absolutely is a bad idea.

The good reason is they just want to have a trip in US. It will be very helpful if you can providing a letter detailed and reasonable trip plan for your parents visiting US. Another important thing is your parents should provide the strong relationship with China and make immigration officer believe they have no immigration intent. Their other kids in China, their job, income, money and house and so on will be solid evidences.Sometime, you know there is no reason to deny the B-2 visa. Just try again and they will be fine.