Del, it's funny you posted that, I noticed exactly the same thing recently with the reflection.
2 sheets of glass underwater generate a mirror, if you look at the tank normally thorugh the front, the sides are mirrors. But of course they are not mirrors to the fish, they can see out of them. So can you if you look at the tank lengthwise.
I looked at the aro tank through the top with no cover, and on the patches of tank with no sand, there was no reflection at all, none, only the brown card underneath.
So this finding should conclusively prove that drop eye is at least not generated by bare bottom tanks. And if bare bottoms tanks is your thing, at least you don't have to worry about any fish staring at their reflection.