Re: why is the fact that a bug won't touch it a good thing?

The whole issue may related to the pores on the fruit, whether they've been treated prior to transport with a wax or other substance - or not, that controls whether insects will attack. If the pores remain open, then tiny molecules of aromatic character may escape the fruit and attract insects. For cases where the pores are sealed, such as by wax, those molecules do not escape and attract insects. thus, the refractive index of the fruit may have little to do with attack.

"Water glass" , sodium silicate, is used in preserving eggs it fills the pores in the eggshell, preventing entrance of air.

A person not knowledgeable of this fact might find one treated egg, and one untreated egg and notice that one of them spoils quicker than the other. They may have measured the refractive index of an egg representative of the lot before hand, or noted that one egg was brown and the other white. Either case, they would make the erroneous conclusion that the refractive index, or color of the shell had anything to do with the propensity of the item to spoilage. Same probably holds true with regards to the fruits' view of the fruits.