I really dislike if software ignores my setting of $LC_MESSAGES=C and shows me its UI in German, just because I set $LANG=de_DE. I hate that. I don't want no UI strings in German, the translations are mediocre. I want everything else in German (paper sizes, ...), but no strings please. That's why I configured my locale settings this way. I don't want those settings ignored.
Please, developers, read through locale(7) and related man pages before you hack up i18n support. Thank you.