How to Name a Movie in Hong Kong

One word: homonym.  "Let Me In" becomes "吸血兒凶,"  a word play between "murder suspect" and "a child who kills" or "an ominous child."  By the way, a stern warning: if you are a bona fide movie snob, don't watch this American re-make because anything American is just shallow, let alone an American re-make, that would be too crass for your refined European taste.  Watch the original,  without English subtitles.  And better still read the original novel in Swedish.