Snake Repellent Testing - Advice

A real scientific test would require time, money, snakes and bait. You would put the snakes in a large enclosure and place baits in two equally accessible areas one of which was defended by your snake repellent. You would then observe over time whether the snakes avoided the defended baits. For it to be a true test, you would need to test it with various types of snakes, since they all don't hunt and probably don't get repelled the same way. Then you would have to test the durability of the product over time and weather. Then you would have to be sure all it does it repel snakes and not poison pets or children or attract something equally as nasty like scorpions.
I hate snakes. For me the best defense is keep everything around buildings and the like clean and clear. If you keep away things that attract snakes (rodents, birds eggs, shelter etc.) the snakes will stay away on their own.