Thanks everyone for your input.  If nothing else, this was a source of interest and curiosity.  But, unless the maker chimes in, I guess this will remain a music mystery.  

If you Google "true temperament frets" you see lots of guitars with the squiggly frets.  Makes you feel like you poured bourbon on your cereal instead of milk.

I doubt that's what's going on with the Goodwill dulcimer.

--
Dusty T., Northern California
Site Moderator

As a musician, you have to keep one foot back in the past and one foot forward into the future.
-- Dizzy Gillespie

I've seen some guitars made with slanted or curvy frets. It's an overly-complex way of avoiding a compensated bridge. A compensated bridge is a heck of a lot easier and gets the job done, maybe a tiny bit less precisely than curved/slanted frets.

--
Site Owner

Those irritated by grain of sand best avoid beach.
-Strumelia proverb c.1990

 I just looked at the pictures, and I don't recall ever seeing anything like that. Maybe some weird attempt to compensate/intonate for string thickness; but 30 degrees seems 'way off the mark?     If it weren't for the ludicrous 33 pound shipping weight for a $30 shipping fee it might be worth the $15 bid price just to see in person.  

"Shopgoodwill" has an interesting duclimer up for auction (refer "Unbranded 4 String Wood Dulcimer").  It's obviously very old but the distinctive characteristic are the frets.  Instead of being installed perpendicular to the fretboard, they are positioned at about a 30 degree (estimated) angle from perpendicular.  I've never seen anything like this on a dulcimer or any other fretted instrument.  What do you make of it?