The game has plenty of no sell and no desynth gear. Anything you can get for free(think artifact gear from ShB or later where its just on a story vendor) doesnt allow for either sale or desynth so you cant just print free money. They also block the current tier of non-crafted gear(so tome gear, alliance gear, raid gear), my guess is this is to prevent people from accidently getting rid of something they really need. The only no discard gear i know of is from veteran campaigns/collectors editions bonuses/pre-order bonuses and some of the cash shop things. And aside from the cash shop(i have no knowledge of those items as i have none), all of them should go into the armoire and thus take no inventory space and not count against your glam dresser.