What does cleaning your house / uniform do in Die2Nite

Simply placing decorative objects in your home is enough, there's nothing else you need to do. You'll gain the effect of the item as long as it remains there.

The padlock you found prevents other people from stealing from you when you're out of town. Other items may provide decoration points which are granted to your soul when you die.

Here's how it appears to work

1. Start by spawning zombies at buildings (day 1)
2. For every night, for every tile:
   • For every neighboring tile with zombies, there's a chance of one more zombie spawning
   • For every two zombies killed in this tile, there's a chance of another one dying by despair.
3. If the total number of zombies drops below 2 × map side × day number, spawn more zombies. (A 12×12 map has side 12.)

We're testing a spreadsheet (live link) that puts these rules in practice in Itching Plantation of Shadows. Time will tell.