Mary raised an eyebrow at Riff. Why the fuck would she make a jab at her, when she could just as easily tell Mary to fuck off? Mary would certainly appreciate it more. But she was being nosy, and Riff wasn't exactly telling her to fuck off. So, she'd keep around.
"Bad sign why?" Well it did look kind of ghostly, but Mary thought she'd ask anyway. After all she'd never been in a security room before.