I have not tried foil but I have tried white spray paint. 2 weeks ago, I trapped my biggest coon of the season in a 1.5 CS, the pan of which I had spray painted white. I set the trap in about an inch of water immediately adjacent to the shoreline just downstream from an outlet pipe on a tiny peninsula and placed the trap in a bed of brown leaves that gave the white pan good visual contrast. I poured frying pan grease on a sapling about 2 feet beyond the trap and also on the ground leading to the trap. I assume this set offered good eye appeal for the coon and would like to think that a possum, and maybe a dog, would not be as likely to go for it? It was also an easy/quick set to make. The front foot of the coon was caught and the jaws were about in the middle of the palm.
My belief is that the coon did not just randomly step on the trap pan but stepped on it for the eye appeal.
I realize this is a sample size of one but it at least worked this time. I would appreciate any constructive criticism of this method.