Well, my brother and I learned a valuable lesson recently. One of his clients (a big client, at that) hired my brother to take portraits. Fine, no problem. Nothing new. He sent me the resulting images for post processing, and then I burned the images to disc and sent the disc to the client, which was the only thing that was out of the norm. All the previous clients either got prints, or an online proof page to choose the prints from. Well, when the client received the disc, they contacted my brother and informed him that the images were horrible. They were graining, looked like powder had been put on the subject's head. My brother was livid, thinking I had over edited some of the photos. But when he confronted me, I couldn't find anything in the photos that fit the description! So I re-edited and sent another disc, knowing good and well nothing was wrong with the images I sent them. Finally, last night (which comes to over a month after the portait session), my brother called me from his home in Colorado. He and I sat and compared the photos, and then he finally told me what program he was using to view the images, which was the standard program for previewing images in Windows. Well, suddenly it started making sense, so I opened up one of the images he pointed out as having the most problems. Oh my freaking God, man. I have never seen a photo more distorted! It literally made the subject look as if glitter had been thrown in her face. So we learned that the key thing when selling the disc itself to the client: Never let them view it on anything but a program made for displaying images at the proper magnification, otherwise they'll see an ugly moire pattern covering the entire image.