I'm not exactly sure how diguises work code wise. I just know they eventually fade/fail a roll and people can tell who you are.
And, it seems to be the only way to regain your disguise, is to remove the helmet/hood/shroud and wear it again.
Be pretty cool, if you could simply "tease" an item that provides a disguise and thus readjust your hood/helmet/shroud to better cover your fugliness.