You can get a report of battery health from the seller, if it's coming from an MG dealer. Lots of people fast charge their cars a lot and they're fine.
Also, you can presumably check the seats and so on yourself.
A friend recently told me about someone who had had a "bomb" put in his car. It seemed fine when he bought it, but over the following weeks it became clear that the previous owner had been a heavy smoker, and the smell of smoke got worse and worse. It had permeated the upholstery and the dealer's attempts to clean the car had not been effective.
He found out about this service where they essentially fumigate the cars by putting something that emits a vapour that removes all smells. Chuck it in the car, close all windows, and retire to a safe distance. The company said that most of their business actually came from car dealers preparing second-hand cars for sale. Apparently it worked, and no more cigarette smell was experienced.
