This has bothered me too. We do know from George's interview with the FBI that there were over 1200 indiscreet photos of Casey that were found on the computer at home. The FBI agent described them as "real bad." I have wondered, since Casey was into photography, if she wasn't attempting to set up a little *advertiser censored* operation starring her. She may not have gotten far enough that she sold more than one or two of the photos (such as the one we all saw months ago.) I think she might have taken the photos and been working on them in Photoshop - realistically, most photos need some enhancement to remove imperfections. That can take up a great deal of time.
The question as to why none of the neighbors ever noticed her returning home has always puzzled me. I realize a lot of people might be working, but even so, everyone has sick days and days off, so I would think someone would have noticed it. Either that or Casey just had incredibly good luck in never being noticed coming back home after George left. But then, that's another issue - George seems to have not been employed quite a bit, so when he was off work, where did Casey go?