A fake is a lefthanded compliment to some work of art that is probably priceless. The artist who fakes another for some pecuniary advantage has already conceded the field to another. Instead of outing his inner vision he aims to make some quick money. In a way his own worth, his signature he has hidden in that of another.
Celebrities have their hangers on and celebrated paintings invite fakes inevitably. He who drops names think it will add lustre to his own insignificant name. These nobodies who sponge on the famous imagine a little of their fame rubs on them by association. Only when they are squeezed dry by their vain pursuits they shall realize they played the fool and wasted their precious gifts for nothing.
Great Painters like Monet, Dali, Picasso have all had fakes passing off as the real thing. Art is a big business and in the cut throat world where an original da Vinci or Titian is few and far in between any discovery of a work that has been lost or put up for auction creates sensation. In order to verify an original beyond shadow of doubt there are many tests. Any error here could spell loss of millions. So the work of the great master must first be established and a fake must be shown for what it is. The difference between the two is that the original work will bear the inner strength and dynamics of a life that led to the work.
There has been so many fakes that do not fool the expert eye. For example John Constable has been copied over the years. It might be that faker had copied the original daub for daub and followed the quirks of the painting faithfully. Still the inner energy with which Constable painted it cannot be faked. Picasso of coursed faked his own paintings still his energy went into his works.
In the canvases that Gaugin worked while he was in the South Ses, thin paint layers tell its own story: being away from Paris he could not afford to waste his limited paint supply. His choice of material for example his canvas of cheap weave is another clue: such tracks of life no fake will adequately cover from another age. Patina of an original and covered with varnish will bear the breath of the artist. There are so many tell tale signs of the genius that a fake shall never recreate.
If only the fake artist lived his life honestly and put all that incompetence derived from lack of inner vision into his canvas it would have been something.
Great artists have in course of their career studied the works of great masters. In order to understand the artistic vision of Eduoard Manet it seems Picasso must have done some 150 versions of Breakfast over the Lawn. Here also Picasso took an existing work of Manet to create his own version which are two different paintings. By fake I do not mean such variations but whatever that negates the inner dynamics of the artist for that of another.