I think having a drone with camera is an absolutely wonderful toy, if the range and battery life get a bit better than current consumer versions... you'd essentially be able to fly!
But one can definitely imagine a massive use of these for watching people in the nude either for personal use, 'journalism', blackmail, or peep-show porn sites.
Even if it's illegal to peep on people, catching anyone who is using a drone would be a nightmare so banning the sale of such products might, unfortunately, have to be the reasonable solution. Of course people can still built their own but then it goes from a mass-consumer-problem to a minority problem as few people could be bothered.
There's an Arthur C. Clarke story (with Baxter I think) which talks about the death of privacy. In that case it's due to the ability to open mini-wormholes but the principle could be the same.