Why were the nails on the pinky finger of the left hand grown long during the time of Louis XIV?

I believe it was helpful in their sniffing snuff.

Where did the extra-long pinkie nail com from? Here are a couple of theories:

Originally it was an organic means of scooping snuff, cocaine, and other inhalant drugs up to be sniffed. Later it became a symbol of belonging to a counter-culture, currently amongst Goths. Some Goths claim that they use it to hold the sugar when they pour their Absinthe. OK, whatever. Independent of this development is the custom in various parts of the word for keeping one long and sharpened nail to open envelopes.

http://www.articlesbase.com/careers-articles/a-fashion-career-fashion-mysteries-explained-70476.html

Louis XIV required his courtiers to scratch at his door with their left pinkie fingers rather than knock, and some grew that nail longer than their other nails for this purpose.

http://parisatelier.blogspot.co.uk/2009/01/how-rude-madame.html

I was told by Greek pupils with the long nails at school it was to pick their ears and nose more easily which is the most common likely reason. http://shanghaiist.com/2013/11/04/yes_the_long_pinky_nail_is_used_for.php (satguru)