I've managed to reproduce this a couple times, although it's random. This is how it occurs. I know the stoves don't work but I keep one for when they do.
- Find a Portable Gas Stove, a Gas Tank and a Cooking Pot or Frying Pan. Try and make sure each one is in a different condition. I.E. 1 Pristine, 1 Worn, 1 Damaged.
- Put them together in your inventory to form the fully assembled Gas Stove and place it in storage on your character or in your tent. This also worked before the tents as well on just your character. Notice that when you "View Contents" each item still has its own individual condition.
- Now just play for a while. Some of the time it happens out of nowhere but usually after a server restart or after changing servers.
- Eventually something will bug and when you look at your stove ALL the parts will have taken on the condition status of one of the 3 items you used to build it.
In other words all of the assembled stove (Stove/Pot/Gas Canister) will be in the same condition after the bug. This condition will be taken randomly from one of the parts and applied to all of the parts that make up the fully assembled stove.