"Inspired" or just straight up copying?

Working, breathing and living in the fashion industry you often (well, way more than often- try every ten minutes) hear the word "inspired." Desigers are inspired by nature, the street, other designers, movies... the list goes on. But where does the line between inspiration and just straight up copying get blurred? Indian designer Sabyasachi Mukherjee explained to Suzy Menkes from the International Herald Tribune he was "inspired" by the "Frida Khalo movie" to put braids in the hair of all his models during his runway show. Why can't he just say he fully adopted the look?? In fact, why can't all designers just tell it like it is- "Oh yes," says designer X. "I totally copied Valentino circa 1975 for my new collection."  I don't think I would respect a designer any more or less if they were just honest... just sayin'.