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Only ever stayed in one once and would recommend them as a great place to stop for a night, cheap compared with many places and their tea is very nice too.
Looking at where the camera was sited, high up, flat inside the wall and behind the shower head I doubt very much was seen other than the opposite wall.
Cameras in vents is surely old school. These days the cameras will be behind the mirrors in the bathrooms and bedrooms. Mirrors will be see-through on the other side and screwed to the wall so you can't get behind them.