I just was working on a small fort in a 'Terrifying' biome and ran into a unique (to me, at least) problem. Everything was going pretty well, save for these massive noxious ash clouds that would blanket the surface and injure any dwarves that came into contact with it. The only real threat combat was was during sieges, because the goblin race would always bring tame war Cave Dragons and seriously mess some shit up.
So I'm about 4 years in, and after a particularly messy cleanup on the surface, I get a caravan. I notice I have almost no crafts made, so I set my craftsdwarf workshops to legendary only, and tell them to start pumping out the goods. Nothing happens.
Confused, I start investigating and remove the manager profile. A legendary stonecrafter runs up, and stats producing goods but they're all generic quality, just 'granite ring', 'granite amulet' and so on. Even more confusing.
The merchants finish unloading their stuff, and I have 'em haul up what I have, only to find my appraiser has no idea whatsoever about the value of goods. It's just blind guessing, and he's annoying the trader half the time, giving the fort away the other half. I start to suspect my game is bugged, and go back to look at that manager/broker, trying to figure out what's wrong.
Tabbing to health, I notice right away: He's blind! I quickly replace him with the next dwarf with appropriate skills, and try again.
No dice, same result. I take a peek at the new manager's health... oh, he's also blind... I try a few more replacement.
Blind. Blind. Blind. Vision lost. Vision lost. Vision lost. Every single dwarf.
Including my craftsdwarves. Every dwarf in my fortress except a couple of the military dwarves is blind.
It took a little backtracking, but I figured out what happened: Nearly everyone pathed through a noxious ash cloud, blinded themselves, rested up, then went back to pretending like they weren't blind in typical dwarven fashion. The thing that amuses me the most though is imagining them all trying to pretend to each other that they weren't blind, like the broker just being like, 'Uhhh... yeah, let's trade this for... how about... THIS?' *points at random item* and the just nods slowly. The manager stands at his desk looking over his paperwork pretending he's reading it. No dwarf wants to admit he has a problem like this, so they just keep pretending, legendary stonecrafters trying to put mugs and amulets together just based on feel. Anyway, I got a kick out of that, so thought I'd share.
It might be nice to get a little highlight on any character that has a disability that precludes them from performing in the task that well (or really at all in the case of manager), but I'm not sure how common the problem is.