Wiping a screen with toothpaste (not the gel kind) supposedly works for fixing scratched screens. All it did in my tests was make the screen shinier and seemed to add small abrasion marks. I also tried toothpaste on a plastic screen protector, such as the kind that comes with OtterBox phone cases. It worked great on that! So it's a no for screens, but a yes for plastic screen protectors.
Erasers work great for making scratches disappear. I used a white rubber eraser, but you can also use the type that's found on the end of a pencil. Simply rub the scratch left and right with the eraser for about 60 seconds, and then rub it up and down for 60 seconds. The friction softens the eraser and it fills in the scratch. Don't press down too hard, though!
Car waxes and headlight lens creams are supposed to be effective at removing scratches on screens, so I gave Mothers PowerPlastic 4Lights headlight cream a try. It made the scratches fade significantly, and l liked the shine it gave my screen.
I wasn't sure about this tip. Sites say to mix the corn starch with a little water to make a paste, rub it on the screen with a soft cloth, and then wipe it off. It didn't do anything to the scratches, but it made the screen shiny.
OK, this one freaked me out. A lot. Putting gooey, oily stuff on electronics is never a good idea, but I gave it a shot in the name of science. I dabbed a bit on as recommended, and rubbed it into the screen with a tissue. As I feared, all it did was make the test screen oily and sticky.
Why do people think it's a good idea to rub food on their phones? Nope, rubbing a banana peel on your screen won't help it. I tried it a couple different ways and it just left a crusty mess that is hard to remove.
Powdered cleanser like Bar Keepers Friend, Comet, Ajax and the like seem a good idea for buffing out scratches. They are slightly abrasive, so you'd think they'd polish your screen to a gleaming scratch-free shine. Well, they don't. They can even leave new little scratches on your screen. Yah, this test didn't go well.