Yes, that was exactly what was happening with my models. I'm guessing the oddness comes from trying to make a frosted glass? Your middle vase I think is the closest to what I was trying to achieve. You least got most of your model to show, mine was all black.. I guess because of the specific jpg I used? I almost always use Jpgs because they are easier to change IMO then gifs, I use gif almost exclusively for animations.

Just an off the wall question, but if the renderers used algorithms, I assume, to make their calculations for light shadows and such, why don't people use vector graphics instead?
Wouldn't a vector graphic be much easier to formulate inside of a model?