How Stupid Is "You"?

One of the infuriating aspects of translation exercises in which one of the languages is English is the ambivalence of "you". Although the standard varieties of English are content with this ambiguity, an informal style which arose from an excess of formality, the common language is not, as the proliferation of forms such as  "yous", "y'all", and "yinz" attests. If the exercise in question involves English only, the ambiguity remains a minor annoyance. If another language which does not treat familiar forms so cavalierly enters the situation, the :"you" problem becomes critical. Many European languages use the second person plural as a polite singular, and others retain the simple singular/plural distinction. Often I use "thou" in my language notes, thereby transforming the familiar term to a technical one, and eschewing the hideous parenthesis (pl). This method, however, is analogous to the abbreviations we all have used in note taking - it suitable for private use, but would confuse and annoy those from whom we recieve grades. In Latin and Greek learning texts, the distinction is clearly marked, and expected to be noted, but in more casual texts of the modern languages, the poor Anglophone does not know which to use. At least in European countries politeness is the criterion rather than ethnicity!