Sadji would, perhaps, give him that there were certain things in her past that she would want to hide... But she wouldn't. She had long since grown too old for secret keeping. Eventually, she would be forgotten and all the knowledge she had would be lost as well. Why not pass it on while she still could? Sadji had no earthly concept of how long she would live without being taken down by some ballsy hunter. But the conversation was essentially over for now and she was allowing herself some extraordinarily close examination. How long would it take for Sherlock to notice the real oddities?
If anything could be said, Sadji was the perfect little patient (corpse). She didn't resist whatever movement he wanted, stayed unearthly still for him. There was no saliva mess to worry about getting in the way, no yawning out of boredom, and not a single attempt to bite him. She made an amused sound at his comment about her dentist but fully expected him to be finished sooner rather than later... But he lingered and she quickly realized what he was trying to figure out. The lack of breath was incredibly noticeable this close up. She was very pleased when he nearly cut his finger on her fang but was also glad that he didn't. That would spoil the fun of tasting him later.
When he finally backed off, she let her mouth close with a firm snap as if to show just how strong those 'implants' were. Her smile grew very broad as he continued speaking and she tapped her fingernails (kept long and neat but slightly pointed - almost like claws but not quite) on the desk, waiting for whatever he wanted next. "Oh? Am I cold?" she asked in a tone that said she wasn't at all surprised, "I suppose I should have eaten someone first." Now she was just being an asshole. "I don't breathe," she stated easily at his question, "And I don't have a heartbeat. You're welcome to check." This was so fun. It had been such a long time since she'd played with a mortal, like a cat with a very bright but ultimately caught mouse.
Wait, remove her lipstick? She made a face, rolling her eyes, "You think a tissue is going to do that? This?" She rubbed her finger on her bottom lip quite vigorously, "Doesn't smudge. It's expensive." Sadji made a gesture with her hand and a drawer opened behind her. From it, sand started pouring out of the drawer - only it was going vertically so it could carry something out of the drawer and across the top of the desk to her. She picked up the package of make-up removal wipes and used that to be rid of her lipstick. As she did, the sand casually returned to the drawer which then shut. "Come on then, detective? How old am I? You've already failed twice - you owe me a meal. But figure it out anyway for amusement's sake."