How about this one. I hire a 172 or something and go for a burn around the bay. It's a lovely clear day and I take some pictures as I go. I land, taxi in, shutdown, pay and go home.
I have a licence and current medical, the W+B, fuel etc was all ok, I had all my required charts and documents, the aircraft has a MR and everything is in order.
My flight was safe and completely legal (actually just re-reading 206 it seems it might not have been).
If I then 3 weeks later decide to sell one of the photos my flight retroactively becomes illegal (assuming it was legal in the first place). With absolutely no difference in safety.
In the back of my mind I remember reading something buried deep in the regs somewhere about aerial photography only being for when you are selling the photos but now I can't find it.
Does that mean if you take photos on a private flight it suddenly becomes AWK?