The reason why Bleach is called Bleach is the following: The producers were asking themselves which color they associate with a shinigami. The answer: black. But black is too obvious so they took white. But calling a series "white" would be stupid so they thought of a word which they associate at first with white. 2 possibilities: pale and bleach. And since pale could also mean that you're physically sick they decided for bleach. And that's why Bleach is called Bleach.