Wrong: It usually signals a room rental by two people who want to be alone and intimate either because they don't want their spouses to know or they lack the kind of privacy they would like at their place of abode. Either way, its none of the LEOs business.
See post # 4,194. Should have added you to the ping.
Your libertarian opinion conflicts with the successful arrest and conviction of drug manufacturers, dealers and users in my small town. The adulterers and fornicators won't be arrested or convicted. We run the plates looking for previous involvements before any further investigation. If the hotel management calls, we have sufficient cause to knock on the door. The drug parties tend to be loud with multiple unregistered guests in the room. The stench from the meth cookers is easily discernible outside the door. Instant probable cause.