Is post-processing allowed, for example? If yes, everything including light spikes could be claimed to be artificially added, not resulting from using different equipment. If pictures are required to be straight from the camera—well, there still are inevitable pre-production and (more importantly) RAW conversion steps.
> There's a need for more complex regulations here.
I'm not sure about that. The general "don't be a dickhead" rule and the resulting public stink for those who don't follow seem to work ok in this case.
You raise valid points, but taking a photo with a professional DSLR camera instead of the phone camera you are advertising goes way beyond post-processing.
> Well, there still are inevitable pre-production and (more importantly) RAW conversion steps.
Sure, but there is a standard procedure to get a photo out of your camera and onto your Facebook page, and that's pretty much the standard amount of processing necessary. I'm more interested to see what the photo would look like if I made it with their camera, than what a professional photographer with a DSLR and a Photoshop license can do with it.