I haven't tested vibration of foods, but I have learned to pick out a good nut when I see one. I'm really good at picking out good apples and avacodos too, I think being "colorblind" helps alot. I will add that I am vibrating quite well these days, so if thats a reflection of the food, then maybe I'm being lucky. How does one test food for vibration ? So far I've been testing my food using only my tongue as a final quality control measure.