Do anything that changes status of an item - e.g. mend "badly damaged" pants with sewing kit
Mouseover item - status is not changed
Inspect item - still no change
Exit/enter inventory - no change
It still says "badly damaged" for like a minute, then changes to "worn"

It work the other way as well:

• Have a can of beans
• Get hit by a zombie
• Beans are pristine, but when you you try to eat them it says "too damaged"
• Inspect beans, says pristine
• Move beans in inventory and/or wait a minute, and it changes to "ruined"