While the concept of being paid to dispose of things nobody else wants involving pay is a decent idea, I think there might be a better way of simulating that than simple negative value.
Incidentally, the topic has come up in reverse, before.
Negative wealth would be a pretty simple way to pay a trader to take away a corpse--unless a negative value would screw up the code somewhere--without a complete overhaul.
I was thinking more of what hill-dwarves sending corpses. Yeah, player forts would just bridge smash, but AI isn't that smart. It would also add flavor to the game, a mechanic not currently in play.
I did do a search before posting--it didn't pop up on the first page. It isn't reasonable to comb through pages of search results, also the concept of negative wealth is diffeent enough from that post to deserve its own thread.
Fortresses generally accumulate tons of corpses over time, especially as wealth makes it an increasingly more attractive target for sieges.
Therefore. As a fortress gets more wealthy, it gets less wealthy. Wealth is inversely proportional to itself.
Although giving corpses to a caravan to discard them isn't too bad an idea.
You just described a feed back loop. More wealth=>more corpses=>less wealth.
When it comes to trading the trader would need to give the fort more wealth to make up for the loss of wealth due to trading corpses. A necropolis could build up wealth.
This was probably discussed in the other topic Kohaku linked to but why can't dwarves just incinerate everything they don't want? And dwarf corpses would get coffins or at least slabs as is proper.
Caravans would be easier than individually selected each gobbo corpse for dumping... setting up a garbage dump under a bridge or over a lava pit...
Just go to "Corpses" and throw them at the caravan.
Although I'm not sure if this is possible in the vanilla game, yet. I know there's no corpse tab.
Yeah, a player fort would just dispose of corpses. Hill dwarves would bring corpses in additionally with a payment to dispose of the corpses for them--ceremonially of course. Don't want corpses? Don't trade for them.