Well, the dead Americans in Somalia and in Iraq are pretty infamous (the ones that hanged from that bridge) but I think they were mercifully dead, and not prisoners.
Just reading a book on the history of the Gurkhas. There was an occasion in Burma where a Gurkha battalion routed a Japanese unit, leaving behind many dead. The white officer in charge ordered the Gurkhas to bury the enemy where they had fallen, in narrow one-man slit trenches.
The Japanese were left for a couple of days at this point, and rigor had set in. So the Gurkhas - quite sensibly, to them - started cutting apart the bodies with their kukris in order to fit them into the slit trenches for burial. The British officer in command, also quite sensibly, to him - ordered them to stop and dig proper graves so that the bodies would not be desecrated.
Personally, I thought it was wrong to publicize photos of dead Iraqis, there should be respect for the dead no matter whom he fought for or pledged allegiance to. As you rightly point out, sadly, this is not always the case.