Years ago I had a small closet grow in a rental where the owners were out of the country and they had friends of theirs acting as their agent, all utilities included. Eventually the landlords decided we were doing something weird, because their electric bill was "too high." We kept telling them there was nothing weird going on, but eventually they sent their friend over to do an inspection. By that point we were already planning to move as our lease was going to end, which provided some cover - I broke down the closet grow, put the lamp back in its box, cleaned the closet really well, and moved everything into the bedroom across the hall. Friend came and took a quick look around, I told her the other bedroom was full of boxes and was a mess, she was okay with not looking in there. Not sure that poor lady was even getting paid.
Later, after months of the landlords harassing us via international call, we finally got them to send us copies of all of the bills. Turns out we did use slightly more electric than them, but not by a huge amount, and our gas bills were much lower. All in all we were basically even, if not even saving them a bit over their own use.