fakeedit: Your new conviction ninjas me a bit, but here's some food for thought from my head, still, if anyone thinks it worth reading... consider this the most passive of suggestions, however, if indeed that.The faster-rotting stuff would be things with a water covering in a non-watery environment. At a low (but not-cold) temperature so that the clothes don't dry (or get preserved).
(Technically, if you piled things up a bit, you might get that effect in a set of clothes sitting in shallow water, wicking the liquid up into the topmost clothes, but it'd probably end up slumping down so that all remaining rottables find themselves under the water level in anaerobic conditions... A pair of trousers would just lay in a 2/7ths water puddle without noticable rotting, or at least without noticable gaseous emissions although it might foul the puddle.)
Maybe the presence of a mist-generator (or, at least, the presence of mist, howsoever caused) would be conducive to open-air rotting. It would be an interesting counter-point to the mist-generator keeping your dwarves generally happy to find that it also means that worn clothes degrade quicker on dwarves that pass through the area, so need more support to prevent the resulting unhappy thoughts of slowly losing their fine clothing...
I do feel that clothes tattering but having no obvious method of recovery/re-use/recycling (or even of sorting damaged ones separately from the non-damaged ones) is a little bit of a blatant omission when there's other realism-simulator levels of detail (including the accumulation of damage to the clothes, itself) so freely given. I don't know if I'd go for miasmic rotting towards syndromes (unless there's something in the plant/whatever materials that's psychoactive or bioactive when released in that way, and Forgotten Beast Leather items might be interesting to
wear, if not prepared right).
Charcoaling non-wooden items intrigues me (although I'm again not sure as to the viability). But repair and patching is probably the thing to look at... How about an *item* that becomes an X*item*X (or x-bounded, but an XX-ed one might be too far gone) can be mended into an +~*item*~+ (the "~" being a "mended" equivalent to the "decoration" modifier[1]), or perhaps an even better quality, in the right hands. Mended again it becomes (perhaps) -~+item+~- (original mends becoming the substrate quality), and there's a chance (where a no-quality mend is made, or some other critical failure that is available at a low level to even the most legendary craftsdwarfs in the appropriate skill) that the item is destroyed.
(And when I'm adventuring, I just want to wander up to altar of the temple of Gapp, or into Griffith's leather workshop. But that's what happens when you start to mix your game-settings up.
)
But this is just me making what is probably a rehash (whether consciously or not) of old arguments.
[1] I don't currently know whether if that
also exists, the mending modifier should be applied externally or internally to the double-chevron decoration assignment. Possibly outside, if at all, but I could also imagine that mending would actually
replace existing decorations (whilst removing the wear'n'tear modifiers, and that a mended item would then be open to be re-decorated on top (and externally to) the mending modifications (i.e. the mending modification tags).