Modern Art

I was listening to NPR the other morning and it was a piece on David Hockney. He is famous for his painting of a man standing next to a pool and there is someone swimming underwater to his end.  This painting recently sold for over 90 MILLION dollars.  It first sold for 18 thousand dollars.  The picture included here is Spring in Yorkshire and I like it because it is a bit representational.  

I don't mind the wilder modern art at all.  But I do rather object to the pieces that are nothing but a canvas covered completely in white paint.  My genuine question is this, given that someone may possess the taste for and truly appreciate the effort and artistic effort it took to paint the white picture, how many counterfeits exist and how would one prove it and would an art insurance agency touch it with a ten foot pole. ??