My first question I would ask anyone claiming these fans do any good is do you actually monitor your fridge temp or are you just assuming they do anything.
My fridge will only get down to about 40 degrees on a good day and a warm day it hangs around 45 degrees. I was looking for answers and found forum posts on the fan pictured above so I decided to buy one and give it a try. Well my fridge now get down to 40 degrees on a good day and 45 degrees when it's hot plus the neat little fan also draws power off my batterys. I have tested it a few times and now it just hangs in the fridge waiting until I decide to test it again like something magical is going to change.
Money would be better spent on a wireless fridge freezer temp monitor so you know exactual what temp yours is running at.