Fabreeze is your friend. Spray some on a cloth after wiping the camera down, and wipe the camera down with it. I once bought a camera outfit (US Army Super Speed Graphic) and the case smelled like it had been sitting in a wet basement for 40 years (probably had been). The case being metal (Haliburton) with felt lined metal dividers, couldn't easily be washed. I tried everything, and it still had that musty swamp smell (far worse than any cigarette smell). The Fab took care of it nicely and 6 months later when I sold the outfit, still no hint of the swamp. Yes, I did disclose the full condition of the case. It had also been painted gold which covered the nice olive drab original finish. Goof off took care of that.
I'm not really sure though what you mean by "Inside" though..
Unless the inside of your inlaw's house looks like This, I wouldn't worry too much about it. It's cleanable (the camera).