Yes, dust can be an issue over time, especially if your machine is over-oiled and even more if you're in high dust/pollution area of the world and leave windows open regularly or have pets with lots of hair and dander production.
However, if uber-collector Martin Howard can be trusted, perhaps when designing your dream typewriter display room, dust isn't as horrible a problem as you might imagine. See: https://lumicrest.com/showcase-lighting-martin-howards-antique-typewriter-collection/ One imagines that occasional dusting and a can of compressed air will do the trick.
You could also do a nicer dust cover/mat the way Tom Hanks does: https://boffosocko.com/2025/06/16/tom-hanks-ingenious-custom-typewriter-covers-mats/
For my refurbished machines displayed in the house (where we have had a monster German Shepherd who sheds all year long and lots of exterior dust from Southern California pollution), if they're not in regular rotation, I'll drop a sheet of tinfoil or plastic wrap under the hood to prevent dust coming in through the hood and that seems to be more than enough protection while not covering up the entire machine.
reply to u/harperjones at https://old.reddit.com/r/typewriters/comments/1whqodm/closed_cabinets_for_display/