Skepticism? Fair enough...Here is a pile of corpses, victims of the 1988 gas attack on Halabja, Iraq. I doubt the folks in Halabja are very skeptical about any claims of WMD being present in Saddam's Iraq...
Photo of a pile of corpses does not prove the allegation by itself. You need to know were the photo originated, the identity of the bodies, time and place of their death and the reliable impartial forensic examination.
BTW, if you have all this additional information the photo is superfluous.
Also if one is shown the photo instead, one should be very skeptical. Photos and TV are the best way to impress the general public - you can show the photo of dead Serbs and tell that they are bodies of murdered Muslims. Or you can show the film with airplane dropping the bombs with false time and place ascribed - the most viewers will believe whatever you say as "film cannot lie".