What to expect from your grease exhaust cleaners (A picture guide)
This is what you should expect and demand from your cleaning company, do not accept excuses for anything less. Also check behind the fan blades and filters thoroughly and inspect or demand clear pictures from both directions at every access plate. If you do not have adequate access to visually inspect the entire duct, hire a competent contractor to install them for you. What you do not see could burn down your restaurant!!!

Before and After Picture Guide:
After

Horizontal ductwork before cleaning

  

Same ductwork after initial gunning
After

Looking toward fan with excessive buildup of carbonized grease

  

Same view looking toward fan after initial cleaning just before touch up and removal of water
After

Smaller sized duct with very old buildup of grease before cleaning, 2 other companies had just attempted cleaning this system

  

Same ductwork after cleaning.

Grease Exhaust Inspection Guide - Complete Job
Grease Duct Inspection (1.4 MB PDF)

Burger King Inspection Guide
Burger King - Down Stack and Fan Blades (228 kb PDF)

Solid Fuel System Cleaning Sample
Before and After