This picture shows a receptacle with burned off contacts, and it was on a display table at one of my seminars.
Yes, the EGC was loose, and the use of 12 AWG is no longer permitted for the "push-in" types of connections.
I believe that UL stopped listing that product quite some time ago. The use of a box for enclosing a receptacle is usually the way in which it gets installed. A box does help to keep the "fault" contained within the box, that's why we have certain rules that limit open gaps and flush .... etc.
Joe Tedesco, NEC Consultant