There are very few mods that are only tung oiled only cocobolo being one of them but that doesn't mean you cant have a cocobolo mod if you live were the humidity is high . I live in Maine and are summers are hot and humid and I have two cocoblolo mods . One has to take better care of his mod is all twice a year put a coat of oil on your mod inside and out and your all set . As long as the mod is treated moisture cant get in . Its not like the mods going to fall apart its one piece of wood if it swells a bit not a big deal bring it into the ac it will be fine
As for which mods have poly most of them do and a couple like ebony and rosewood have lacquer .
The mods that are not polyurethaned will be labeled oil finish . There are some people that dont like a polyurethane finish they prefer a natural oil finish. I can understand this there is nothing like a mod finished extra extra smooth with a natural finish . Its extremely soft and enjoyable to hold and I put a glass finish on a mod when I no its getting a oil finish . Actually I try and do it to all of them but you can tell on a oil finished mod you can feel the grain .
The average person is attracted to a poly finish because of the shine and it really does bring out the beauty in a wood product . But if they ever held a hard wood mod with a natural finish they would no what they were missing .
my first Woodvil is a cocobolo.
like i have said before, if you find anything that feels as good to hold in your hand, you should probly marry it.