OK, here's some believes of the hoteliers:
Every single hotel, there shall be at least a permanent room which should be left vacant at all times. No matter how full the hotel is, they are not to sell that room(s) to any guest. It was said that specialroom was "reserved" for those "special visitors".
So, if you plan to stay in some hotel, always book in advance. Try to avoid walk in. If the receptionist told you there's no more room available, do not insist one anymore or try to bribe them to give you a room. If you do that, most of the time the room you have will be that "special room".
Sometimes those "special visitors" might go to other rooms also, so here's some tips on how to protect yourself:
Before entering your room, always knock on the door first, even you know the room is vacant.
After you enter the room, if you felt very cold suddenly and have "chicken spore", leave the room quietly immediately and go to reception to request to change room. Most of the time the receptionist will understand what's happening.
After you enter the room, immediately switch on all of the lights, and open the curtain to let the sun light in.
Before you go to bed, arrange your shoes so that one of them is upside down. Some say this is representing yin& yang to protect you while you're asleep.
Always leave at least a lamp on while you're sleeping, preferably the toilet's lamp.
If you're staying alone and they have give you a twin bed, do not sleep with the other bed vacant, try to put your things like luggage on the other bed before you sleep.
Have a Nice Day,