hazard means that something has a chance to cause harm so FIRE HAZARD means that an object or something is prone to be caught on fire which in turn cause harm.. So i think it it not appropriate to put "fire hazard" in a hotel as this will mean that something in the hotel ot prone to get burned and will in turn cause harm. It is as if you are warning people that some thing in the hotel can burn easily.. :)

The sign is there to warn people that that particular area is dangerous and may catch on fire.