http://www.mercurynews.com/2013/10/14/few-vegas-casinos-have-hotel-surveillance/
I don't know about the hotels on the upper part of the 'strip' but when I worked at the Four Queens Hotel/Casino downtown as part of the security team, about a third of the camera domes (away from the actual gambling areas) were fake. This was done to still provide the customers a sense of security while keeping the cost down.
Cams in the hotel room areas are all real, especially in the major casino hotels. They aren't generally monitored and are more for picking up perps on cam after a crime has been commited in a room of the hotel (room thefts, rapes, etc) which are quite common.
