Apple Demo

Depends. Daily I am fine with C or sometimes even D grades. Collection I prefer as close to A as possible.

if the screen was shattered but the device was still able to perform all of its advertised functions then that's fully functional daily driver i'd want C grade or better but for a collection (display), A or B

I’d go even further than d tbh, as long as it didn’t cause a dead zone on the digitizer or dead pixels on the screen

Tbh for a daily I'm picky.. I want perfect condition. Same with my 12 pro max currently. Tempted to swap it with Apple care + out when the battery is around 90 just because there's a few scratches on the sides.

If there are no cracks, it’s good for me. For older and cheaper phones I don’t care about the condition. But i got my daily driver in mint condition(1yr old 11 pro max).

I typically keep my daily devices between A and B. On average, my collection devices are actually in worse condition, since they were donated by previous owners who didn’t take as good care of them.

It depends on price and "need".

That's not what fully functional means