Are wrist tattoos a bad idea? Specifically, if I want to work in China or Japan?

Basically, if you want to work in China or Japan...don't get a tattoo that you can't hide. They won't care about whether they can read it or not, but the fact that you have a tattoo will give yourself and the company you'll work for a bad image, and they don't want that. If you really are going to have it on your wrist, then I agree, go cover it up whenever you're at work with a watch or something.