Do cats walk on foil or are they terrified of it?
One of the well-known domestic cat deterrents designed to stop them jumping up onto countertops is to put tinfoil on the countertop. There is a well-known video on the Internet of a domestic cat jumping onto tinfoil and who bounces back off in complete horror. Absolutely no doubt that it acted as a deterrent for that individual cat.
Actually, it's was arguably cat abuse because the animal was so frightened. The fear comes about because the cat suddenly encounters something completely alien to it. The unknown is frightening to a cat. That's why cucumbers placed behind the cat causes the animal to jump in fear. They suddenly encounter something odd and strange and want to get out of the way.
The video on this page is totally self explanatory. Although the cat walked on the tinfoil gingerly, with some uncertainty, there's no doubt that the foil was not a deterrent. I think this is partly because this cat had time to check out the foil by smelling and looking at it, allowing them time to make up their mind to traverse it. It is different when you put foil on a kitchen countertop because the animal does not see it until they are on it.
They think that they are jumping up to an ordinary countertop and then suddenly encounter a strange substance. That's the frightening element of it. I'm not sure therefore if this video really explains what is going on when a cat is frightened of tinfoil, when it is used as a specific deterrent.
All deterrents really are about unknowns to the cat. Cats avoid unknowns or they approach the object or substance carefully to play safe. But, as you can imagine, cats get used to the unknown and when that happens the substance or object no longer act as a deterrent or it is less effective.