[quote=@t2wave]
[@Kirah] What all perceptions does Emily's abilities hide her from? Given that telepathy doesn't work I would assume it's a pretty wide range.
[/quote]

Well it doesn't hide her from the standard smell stuff either. And technically you can see her, but she's got a [url=http://hitchhikers.wikia.com/wiki/Somebody_Else%27s_Problem_field]SEP[/url]  field around her (in the weirdest and most obscure reference I could probably use). 

Edit: actually that wouldn't quite be the weirdest or most obscure since the power is a reference to a power used in Exalted (which I can't remember the name of said power). 
The thing is she's less noticeable the bigger the crowd. Holding Alistair's arm, probably makes her noticeable, but if she let go of him and just kind of stood next to him, she'd fade into the crowd. If that makes any sense. She's also extremely forgettable. Like if you spoke with her, you know you spoke with someone, you may even remember the whole conversation, but her face, if you saw it again, doesn't seem familiar. 

Edit 2: And she has to try to make herself completely unnoticeable, like really relax into it, so if a situation is tense enough she would actually have a hard time calming herself down enough to be unnoticeable. The more stressed she is about it the more visible she is. Though calling it visible really isn't the correct term, because she is always visible. Someone with eidetic or photographic memory would remember her, but she'd seem as unimportant. That's most of what the power is marking her as "unimportant" or as the Hitchhiker's guide reference would allude, she's just someone else's problem.