There are several items (Rook's death Masks for one) in the game that cover faces, however it seems that the only way to determine this is by looking at the person (unless I have been misinformed). If the person is trying to conceal their identity (no matter how poor their disguise is) this can create an RP misstep if someone doesn't realize that something is different and just walks up and says 'Oh Hello (Name)!' So in order to support this sort of thing I think it would help if something was implemented in the short description so you'd know that their face was covered, similar to how you'd see if someone was not wearing a shirt for example.
Something like:
Also here: (Matilda, with her face concealed)