How does the app decide whats good, fair and failed?

As above, ive been scanning several things (admittedly through game, rather than scaniverse itself, as i find ingress works a lot faster than scaniverse does) and them having them activate, ive knky had one fail, though i was sure i was scanning it really well, doing close ups and decent distance away, only about 200 degrees admittedly cause there s a pond behind it lol. But others ive had only go to fair, but when i check the mesh it looks great to me (have posted examples below) and ive even seen some that are “good” that arent even scans of the thing in general but the road beside it or even just the tops of cars

Cause im a new user need to do these pictures one at a time lol

So does nobody answer queations kn here?