Much as passports are very important for proving identity etc, people who travel have had their passport scanned, photographed or photocopied by pretty much every hotel they've stayed in. I'm not sure the shoebox in the backroom in Koh Samui with the photocopies in constitutes good storage hygiene protocols. How that doesn't turn into rampant identity theft I don't know, or maybe it does? Not, happily, for me... yet.
Since then, I do not allow the scans anymore. It is a dreadful feeling showing up to a hotel not knowing if you'll get turned away at the last minute because you take a stand for your privacy. So far, none have been willing to lose the bookings, but I know sooner or later my luck will run out and I'll have to find last minute accomodations.