I’ve read several things and seen references to keeping otter fur wet before put up, I presume to prevent singe? I haven’t had any problems that I noticed with dry otter, but why the emphasis? Do you just keep wetting it and then put it on the board wet?
Does otter fur that dries out on a live otter singe as well? Seems strange. Any insight appreciated.

Dampen the guard hair.It is the guard hair that can singe.
Most singe is caused by dry heat (hanging an animal near a wood stove),or bright sunlight in spring on live otter.
Some trappers scrape otter on a beam after rough skinning,If pushing hard instead of slicing lightly with the fleshing knife dry fur on the dry beam can singe.dampening the beam and the guardhair will help to alleviate that particular problem.
Not an issue for trappers who frostscrape, clean skin,or flesh over their knee with a victorinox skinning knife.
Early and late caught otter often have naturally singed fur not caused by fur handling.
Singe is a problem with Otter because the guard hair has an oval crossection not round like other furbearers.
Singe is normally a downgrade but the price difference may be negligable depending on the end use for the fur.
Prime otter are often plucked and sheared so a manufacturer that is using them for that purpose will pay good money for heavy otter even if singed.

Most otter are singed before you catch them.
How does an otter get singed when drying by heat? It seems to me with the fur in when drying how does heat effect the fur?

Well, I got to get to the deer woods.

Singe shows up in the window and tail.
Hanging to dry in the wrong environment before skinning and boarding is the culprit.
I hang all my otter to dry slowly in the cold room.

Here is a test you can do beav,take a good strait hair grade otter skin with no singe,dried and off the board,and store it in your attic over the summer,then open it up next winter and see it all singed.

I have opened up a few for tanning like that.