There is no one single reason for all those photographs of mannequins, but there are at least two:
Well, every time I buy a new camera, it is dark when the battery is full. Since I don't want to wait until the next day, I usually go to that specific shop window and take some pictures. I also do it, if the shop window has been rearranged or I want to test something.
Yesterday I did it, because the shop window has been rearranged and I have learned a new technique to cope with high ISO in Lightroom. The salesman, who is a fine photographer himself, told me, that he would increase the luminance noise reduction and gets the details back by sharpening. Usually I don't like to sharpen my pictures too much, but like to add clarity instead. I have found, that his tip is really a great one and I could improve my shots I took with my Canon G12 at ISO 3200 significantly.
Yesterday's pictures really surprised me, since I got incredibly clean photographs shot with ISO 1600! Of course, there is still noise in the shadows, but on a DIN A4 sized print (in inches: 11.7 × 16.5) there is no visible noise and the picture looks completely clean with many details like fibers of the hats. This is so incredibly great for a compact camera, that I am very enthusiastic about that.
On the other hand I enjoy photographing shop window dummies and real people in a single picture or shop window dummies and pictures of icons like Monica Bellucci (who is the women in the background of above pictures) or Penélope Cruz, who is a actor I like very much. There have been juxtapositions in my photographs of mannequins I simply like.