I was in NYC the other day and stopped in a deli in a pretty upscale area to grab some breakfast and started talking to the owner.He had an 8' hood with a 6' lateral that went to a 90 degree elbow then straight up,and the fan was on the roof.The store was on the ground floor of a 5 story building.I asked him what he pays to clean his exhaust system.He told me he used to pay $275,but then another guy came in and did it for $195,then he started using a third guy who comes in from Queens and does it for $125.I said $125!!,does he clean the whole system including the ductwork leading up to the fan and the fan itself.He said no they just clean the hood and to the elbow!I asked him how long these companies just cleaned to the elbow,he said about 8 years,"I think the rest of the system needs a good flush!" he said.He was from the middle east,but a pretty nice guy nonetheless.Amazingly he said the requirement in NYC was quarterly cleanings,and they are pretty strict with the frequency. $125!!! I think it does need a good flush!! I think if this guy ever got a quote from a legitimate company to properly clean this system and install access panels he would faint!I almost offered to inspect it and give him an estimate,but my gut told me not too ,I was late to where I had to go as it was.