these guitars appear to be only stained or unfinished, they are
actually finished with the same finish as regular guitars but with a
slight chemical change so the result is flat with no shine. This saves
the manufacturer time in manufacturing and saves you money.
This flat finish protects your guitar just as well as glossy.
A clean warm
cloth then clean dry cloth will remove grimy residue as
recommends not polishing their flat or satin finished guitars with
guitar polishes because they will hurt the guitar's finish.
They recommend using something
called Ken Smith Pro Formula if you want to polish.
Martin recommends not polishing their flat or satin finish guitars with
polish but the finish will not be damaged if you do.
The problem I see
with the flat finish is over time, constant rubbing will turn it glossy
the back of the neck where your hand always rubs or on the body where
it rubs in
the guitar case.
Some guitarists prefer this flat finish because spotlights won't
reflect off the face of the guitar on stage.
Bob, Gman ( o