Showers (and plumbing in general) are a great source of bad design examples. Most modern showers seem to think it's OK to simply engrave icons in outline, which means they are difficult to see when things get misty and wet (shower, right?) and without glasses. Then there is the trend these days to mark the moving surface rather than the fixed surface. Why is this a problem? Imagine the temperature control, let's say it is a dial marked with H and C. Does moving in the direction with the H make it hotter or colder? You might think hotter. But what if the fixed surface has something that seems like a pointer adjacent to the dial? Now moving in the direction of the H moves the C closer to the pointer.

The toilets in our house have dual flush mechanisms. Either two separate buttons of different sizes in the same bezel or a smaller button embedded within a larger one. Is the larger button the bigger flush or is it larger because it is the smaller flush and you should use it more, so it has been made more obvious?