When the pic is of a provider that is either covering up a body part or not showing a particularly part of her body that she obviously doesn't feel is attractive. Examples below.

 1) Blurred facial pics.  It's understandable
    providers don't want their mug plastered over
    the net, but in many cases it's because she's
    not attractive.

  2) The hand/arm over the midsection.  This
     is the classic pose of a provider that is
     trying to hide the fact that she is  
     carrying a few extra pounds in the midrift.

   3) Wearing a garment that hides the fact that
      she may have no butt or not displaying her
      butt altogether.

   4) The pic where the provider pic is cut off
      at the knee.  This usually indicates that
      the provider legs are not in her opinion
      attractive.

    5) And finally, the glamour pic, where the
       provider is so maded up, that when you
       see her, its a good possibility that don't
       recognize her.

This is number 6 for your list: stealing a pic from a porn-star website.  Number 7 - Posing on their stomach to conceal too many cheesesteaks or Taskykake Kandy Kakes.