NEVER use non-ASCII characters in your source code, not even in quoted text. Why? Several reasons:

1. any given machine may not be configured to understand your character set;
2. any given machine may not have an appropriate font;
3. any given editor may not know how to handle that character set;
4. for some characters, users may not be able to see the differences easily (this is no doubt a function of familiarity)

If you need to spit out non-ASCII characters, then they should live in a language-specific resource file. This even applies to code that is only for your own consumption where the bizarro-characters are for your own language, to protect you from the pain of editors that don't know your character set on other peoples' machines, or on mobile devices, or ...

Any use of non-ASCII characters in code is a bug, and any support for non-ASCII characters in code is also a bug because it encourages the writing of buggy code.