Have you used an OXO measuring cup? They really are a lot easier to use when baking and cooking, and my sponges never have a problem getting in those corners.
Yes, I have one. They are really easier to use. I usually have problems cleaning that top corner, my hands are a bit large so I have trouble cleaning that part. Also, I find pouring a bit more tricky when using the cup. I just asked about it to my wife (she bought it) and she said pretty much the same thing.
My main issues with it: the handle broke off, it can be tricky to read the top-down markings when dealing with dairy (fats tend to stick to plastic), and it's hard to mix things in it, due to the shape of chamber. (E.g. an egg yolk or two into the cream I just measured.)
On the other hand, my "pyrex" measuring cup lost all of its markings to the dishwasher, which also makes it a bit difficult to measure anything in it (without a scale).
This happened to mine as well, I was a bit disappointed, expect OXO to be better quality. They'd probably replace it if I asked but I feel like it's my fault since I dropped it, even though a plastic cup should survive a fall on the kitchen floor.
It wouldn't surprise me that the plastic had been carefully chosen to lack the plasticity to stay in one piece when dropped from counter-top height; bet that increases profits for the company (at the expense of wasted resources for everyone).
Actually, this wasn't a drop. I had just washed it and was holding it by the handle. I gave it a shake to get rid of the remaining water and it snapped.
I think the joint is somewhat plastic, to the point that it feels slightly flimsy, possibly to prevent drop failure.