I used to do security and I always wondered about that. It wouldn't be hard at all to wire up a room and nobody ever know. I've always inspected hotel rooms when I had to stay in one, and you'd be surprised at the kind of shit you can find in one if you look hard too.
Supposedly there was this guy that had a hotel and built a catwalk over the rooms so he could spy through vents. Had the motel modified for this. Would take notes. When this (fairly famous) journalist wrote a book on him, details fell apart and turns out he was probably making it all up. Years worth of bullshit, details down to dates and times and descriptions. His wife went along with it all. I don't know what's stranger, actually doing that, or making it up that you did.