
In the Grimm's Fairy Tale Classics version of Beauty and the Beast, Maria gets so sad while staying with the Beast that her emotions turn things such as dinner and flowers, into dust.Any time a Digimon is destroyed, it usually either spontaneously bursts or slowly disintegrates into computer data, which is usually given the visible effect of dust particles.Later in Sailor Moon R, Moon Princess Halation would do this to Droids, freezing them into blue statues which then dissolved into sand. It didn't happen to some Youma, however- one was shattered to pieces after being hit instead. The dub made the claim that it was moon dust, which fit with the general concept of the show. This happens to any Youma hit by Moon Tiara Action in Sailor Moon.If you enjoy Gallows Humor, someone nearby might call out "don't sneeze".

It's also one way to present what seems like a very final death or even a kid-friendly, body-less death, or may be what is due to alien biology. Such conversions often will happen to parts of the object which are far away from the beam at the same instant as the spot the beam is actually hitting. When you're shooting a beam at a large block, you would expect it to turn to rubble or some lava-esque state (or just get a hole) it will instead collapse into a pile of dust.

Early low-budget special effects techniques were able to create this sort of image, and it has been a popular visual since. However, in media it's quite a fun way of destroying something utterly.

Beyond incineration to turn something into ash, the only real way to make whole things into dust is some form of disintegration. That is, it's effectively a waste product of excess and so not easily formed from whole objects or people. Dust is a collection of particles shed from just about everything and distributed through everyday movement.
