Rick asked: “Smartphones that are cracked – besides looking bad, what makes a smartphone that’s “broke”, work improperly. Sometimes the touchscreen will work fine, some days it won’t. Is there a danger to the operations of the smartphone with the screen being broken?”
Rick, sometimes your screen works and sometimes it doesn’t because under the glass there’s a digitizer that is used to sense when a finger disrupts the electric field around the screen.
Capacitive screens don’t care if you touch them or not, they’re not like resistive screens that bend. Instead capacitive screens sense that the electric field near the screen was changed by something that is not the air. That’s done by a digitizer.
If your screen is cracked, the digitizer may or may not be whole. It may have been damaged too. In your case something is probably wrong, that’s why your screen is not always working as expected.
Now, as to whether or not there is a danger from using your phone with a cracked screen, it works out just fine most of the time, but it’s riskier. The phone is designed to have a glass barrier between the phone’s internal components and your skin, sweat, rain drops, and everything else that designers don’t want to be making contact with the phone’s insides. You can also cut your face or fingers, but you probably figured that out already.
Long term, you probably want to get that screen fixed sooner or later something will slip in there and cause some trouble.