[Blissey]

Scarecrows, all variants, do not disappear when they're supposed to -- at least in the overworld (this has not been tested in houses). Instead of lasting the requisite 6, 12, 24 in-game hours, they seem to last much longer. Speculation is that they may last IRL hours instead.

Steps to replicate:
Place any scarecrows on the overworld, and wait to see that they don't despawn when they're meant to.

Server lag may contribute to this, somehow, if at all -- assuming they're not lasting IRL hours.