1. Some friends I know use Snapchat for 'photos they don't want other people to see'.
2. Therefore, most people use Snapchat to send porn.
3. Therefore, Snapchat should be valued as an amateur porn company.
Do you really believe that's a valid argument? And that all of the 350m+ photos sent on Snapchat every day are porn?
You actually don't need the Ctrl key. Just PrintScreen will also do the same thing.
WindowsKey + PrintScreen is a nice idea. Problem is, I usually do Alt + PrintScreen. Adding the Windows key doesn't do anything in that case.
It doesn't disappear, and whilst it might disappear off their servers I can guarantee that won't be the case in the future. At some point a court is going to force SnapChat to preserve a user's photos on their systems, probably someone under a wiretap or surveillance. I wouldn't be totally surprised if this hadn't happened already.
I have lots of friends who use Snapchat (mostly the teen to college demographic), and they all use it for photos that they don't want other people to ever see. They use iMessage or Whatsapp for everything normal.
The user generated content literally disappears in 10 seconds, and you are left with... nothing.