I meant - why not just wipe it? (full slow format)
I hoped the short answer would do, but since you ask again, you will receive the longer answer. I am curious by nature and profession. While working for the federal government, I was also a part-time law enforcement officer in Virginia, mainly working in the Patrol Division but sometimes helping with CID investigations. If something doesn't look correct to me, I will pursue as many rabbit holes as I want until I am satisfied with the outcome, or run out of rabbit holes.
In accordance with the 4th Amendment to our Constitution, anything legally discovered that is potential evidence of illegal activity is fair game for further investigations. Some criminal activities are discovered by chance, and as long as the subject's rights against illegal search and seizure are not violated, then the evidence can be admitted in criminal court. For example, if I stop a driver for a traffic violation, and while I'm talking to the driver, I notice the driver's speech is slurred and I observe in plain sight what appears to be a well-used crack pipe and a large bag of white crystalline material on the passenger seat. This is sufficient evidence for me to continue with another direction in my traffic stop. This did happen, and it didn't fare well for the driver. He unwittingly broke my "Never do two or more stupid things at the same time" rule. If you're transporting just under a kilogram of crack, don't run a stop sign.
In the case of the CF cards, I wasn't expecting them because the advert didn't mention them and there was a hand-written note explaining why the cards were in the box with the camera body. Had I noticed any illegal images on the cards, I would have take the appropriate action based on my training. However, they were images of a not-so-bashful adult female, so I did completely wipe the cards. When I eventually sold the D700 to someone else, I didn't include any cards with it.