the problem is not that you might hurt your wire, but the non wall rated wire may spark, causing a chemical reaction with your wire insulation and your house insulation... often leads to spontaneous combustion... flames have been documented to reach nearly 1200 deg F due to the chemicals burning off.
check the link here:
http://www.youtube.com/watch?v=0P61CJ6OGK0 What happens if you run it under the floor in the basement ceiling?
My question is where do you put it so you cannot see it?
What are the percentage that something will happen?
Wouldn't it be just as great of Chance it happening not in the wall?
