My question involves landlord-tenant law in the State of: California

My ex-landlord claims that the paint above the heater in my room is damaged because of smoking. The heater is electric and located at the bottom of the wall. I suspect that coming heat could make the paint look uneven, but not exactly sure what happened. Or maybe the paint was damaged before I moved in (before I moved in the landlord mentioned that the previous tenant had smoked in the room).
I could smoke outside the house once in a while with a glass of wine on Friday, but I've never smoked in the room, and I generally don't smoke more than a few cigarettes per month. I'm not sure if I can prove anyhow that I didn't smoke inside, and whether it makes sense to dispute the claim given I didn't make any pictures before I moved in, or just pay for painting the whole room. Could you please give me some advice?