Question
My neighbor had a racoon in their attic- and they eventually got rid of the animal but was told that they had to totally gut their entire house to get rid of the smell and droppings because if you don't remove all of this the house is forever marked. The smell and droppings also is very harmful to humans and can cause death if inhaled ove time.

Answer
I am not aware of any research that says the "smell" is harmful. The roundworm eggs that may be floating in the air after disturbing the toilettes can be harmful if inhaled and swallowed, but not the "smell."
As for "marking", so what? If your home is repaired appropriately, the likelihood of reinvasion is low. Remember, even if the "odor" is gone invasion can still take place. After all, raccoons invade homes that never had raccoons before.

I would be concerned about excessive threat claims. Raccoon roundworm is dangerous. But danger needs to be understood in context.

I suggest your neighbor read our literature on raccoon roundworm and our tips on hiring a professional all available at our site http://icwdm.org before signing any contracts.