Some local yutzes (a company specializing in attic ventilation and
fans) here put a bathroom fan in the ceiling above the kitchen stove.
Wrong duct size, not to mention a fan not rated to deal with grease.
The job that was spec'd was the installation of a kitchen fan and roof
vent cap for about $350.
The issue of the wrong fan type wasn't discovered until the owner of
the place got up there to clean the grille and pulled it off to find
the big yellow warning sticker on the fan saying "not for kitchen
use." The owner then found out that there was a fire hazard involved
in using a non-kitchen rated fan above a stove.
Now, to their credit the yutz's did come back and install a proper
utility fan rated for kitchen use with the proper sized ductwork upon
urging of the homeowner. But the homeowner had meniton the magical
word "liability" before a phone call got returned.