Hoods are cleaned in accordance with NFPA96.  We are a fire protection company and not a janitorial service.  Our goal is to prevent grease build up in your hood and limit the fuel source should a fire occur.  We clean all accessible areas of ductwork.  We remove and clean grease filters and we get on the roof and clean the fans.  We inspect belts and replace as needed. 
We take both before and after photos of areas that are cleaned and make note of any deficiencies before and after cleaning. 
Ultimately, other than the assurance of a clean hood and duct from top to bottom, you'll never know we were there.  And of course we will shine it up for you!